Abstract: An antenna includes a solar panel and a signal receiver panel pivotally coupled to and in electrical communication with the solar panel. The antenna also includes a level indicator disposed on the signal receiver panel. The level indicator indicates whether a top surface of the signal receiver panel is horizontally level with respect to a direction of gravity.

Abstract: A non-electronic head-worn system for providing visual inertial head orientation information to a person is disclosed. The system comprises a head-worn unit that displays at least one orientation reference symbol to the person wearing the unit wherein the orientation reference symbol stays in a fixed visual position for the person when the person's head changes orientation. The system also comprises a pitch indicator that gives visual pitch information to the person and a roll indicator that gives visual roll information to the person. The pitch indicator and the roll indicator are responsive to a pendulum, a rolling element, or a fluid in a reservoir. The pitch element and the roll element do not use electricity or electronics.

Abstract: The invention provides a tilt angle detecting device which has a two-liquid tube (19), comprising a transparent container (16) containing a first liquid (17) and a second liquid (18) having different property, specific gravity, and optical transmissivity from each other, wherein a movement occurs between the first liquid and the second liquid by tilting of the transparent container.

Abstract: A system for positioning post sleeves is provided including a pair of post sleeve positioning devices and a spacing mechanism. Each post sleeve positioning device is configured to receive a respective post sleeve and to enable selective adjustment of a position and orientation of the respective post sleeve. The spacing mechanism is coupleable between the pair of post sleeve positioning devices to determine or control the position and orientation of the post sleeve received by one of the pair of post sleeves positioning devices relative to the post sleeve received by the other one of the pair of post sleeve positioning devices. Related methods are also provided.

Abstract: A calibration frame for calibrating a reference system for vehicle measurement has setting elements, which enable a precise spatial orientation of the calibration frame, and multiple defined points of support, which are designed to accommodate a reference system carrier. In one specific embodiment, the points of support are designed in such a way that the reference system carrier is situatable on the points of support in at least two different orientations. In a second specific embodiment, a leveling element is provided which indicates the spatial orientation of the calibration frame in relation to the earth's gravitation field.

Abstract: The dual-globe apparatus utilizes at least one indicator on a tool. The indicator comprises an outer vessel buoyantly supported within an inner vessel. In one embodiment, the outer vessel and inner vessel comprise spheres. In another embodiment, the outer vessel and inner vessel comprise spherical segments.

Abstract: A method and apparatus are provided for reducing hysteresis in displacement sensors by reducing the resistance to motion between components in the sensing units that move relative to each other.

Abstract: A distance indicating mechanism can be used in combination with a bow sight to quickly determine distances to targets from an elevated position. The distance indicating mechanism has a generally circular, fluid-filled tubular device with one or more adjustable indicators located thereon. The indicators are positionable to correspond with the fluid level in the tubular device to indicate the orientation of the mechanism when aiming at a known distance. Each indicator generally corresponds to a sight pin of a bow site that indicates a corresponding linear distance for which an arrow will be at a desired vertical position when shot by a bow operator.

Abstract: The dual-globe level comprises at least one indicator located on a body. The body defines front and rear faces, a pair of opposing ends, and at least one longitudinal surface. The at least one indicator comprises an inner vessel located within an outer vessel, and more preferably, a substantially spherical inner globe located within an outer globe and buoyantly supported within the outer globe. The inner globe, viewable through the outer globe and defining an equator around its outer periphery, is buoyantly biased within to maintain the equator in a substantially horizontal position. The equator is in operable registry relation with a first indicia to indicate a position of the at least one longitudinal surface of the body in relation to a surface or line in question located adjacent thereto.

Abstract: A distance indicating mechanism can be used in combination with a bow sight to quickly determine distances to targets from an elevated position. The distance indicating mechanism has a generally circular, fluid-filled tubular device with one or more adjustable indicators located thereon. The indicators are positionable to correspond with the fluid level in the tubular device to indicate the orientation of the mechanism when aiming at a known distance. Each indicator generally corresponds to a sight pin of a bow site that indicates a corresponding linear distance for which an arrow will be at a desired vertical position when shot by a bow operator.

Abstract: An inclination position sensor where, on a substrate on which wires are formed, plural electrodes electrically connected to the wires are disposed, a conductive ball that can simultaneously contact at least two of the plural electrodes is disposed, an enclosure that covers the plural electrodes and the conductive ball is disposed, and a circular arc is formed in places of the electrodes that contact the conductive ball.

Abstract: This invention, precision level device, provides the leveling of the subjects. An improved precision level device comprises a transparent body including an aperture, a cap, a lower horizontal and upper horizontal walls of the transparent body, the first vertical and second vertical walls of the transparent body, recess, fluid, graduation line(s), horizontal graduation line, vertical graduation line, diagonal graduation line(s), magnetic element, and a front wall of the transparent body.

Abstract: The dual-globe level comprises at least one indicator located on a body. The body defines front and rear faces, a pair of opposing ends, and at least one longitudinal surface. The at least one indicator comprises an inner vessel located within an outer vessel, and more preferably, a substantially spherical inner globe located within an outer globe and buoyantly supported within the outer globe. The inner globe, viewable through the outer globe and defining an equator around its outer periphery, is buoyantly biased within to maintain the equator in a substantially horizontal position. The equator is in operable registry relation with a first indicia to indicate a position of the at least one longitudinal surface of the body in relation to a surface or line in question located adjacent thereto.

Abstract: A spirit level (10) includes a profiled body with lateral surfaces (20, 22), end faces or areas (24, 26), and longitudinal surfaces (28, 30) that form measuring surfaces running between the lateral surfaces, which project laterally over the lateral surfaces with their longitudinal edges (32, 34, 36, 38), as well as at least one position sensor, such as a vial (14, 16, 18). In order to carry out a verification of horizontality or verticality not only in the conventional way, but especially also to assist in maintaining intervals in assembled brickwork, it is proposed to provide a uniform series of indentations (46, 48, 50, 52, 54, 56, 58) within at least one longitudinal edge.

Abstract: A tilt sensor has a source for optical radiation, a pattern support having an optically effective pattern for the passage of the optical radiation generated by the source, a tilt-sensitive unit downstream of the pattern support in the direction of propagation of the radiation, and a projection area for the incidence of the radiation generated by the source and passing through the pattern support and the tilt-sensitive unit, wherein the source is in the form of a pattern support.

Abstract: The level device includes a level body having a pair of orthogonal reference surfaces. A vial carrier on the level body holds the level vial such that it can be calibrated with respect to the reference surfaces by rotation about a pair of orthogonal axes, each of the orthogonal axes being perpendicular to the direction of elongation of the level vial. Adhesive fixes the position of the level vial with respect to the vial carrier and fixing the position of the vial carrier with respect to the level body. The vial carrier includes a vial support and a pivot for engaging the level body. When the vial is calibrated, it is rotated about a first axis perpendicular to the direction of elongation of the level vial, and about a second axis perpendicular to the direction of elongation of the level vial and perpendicular to the first axis.

Abstract: A level having a frame with an edge rail and a web extending from the edge rail at right angles. A web opening is provided in the web. A capsule assembly is mounted on the web at the web opening. The capsule assembly has a transparent capsule having a liquid therein and outer cover plates mounted over the capsule on each side of the web. The volume of the liquid in the capsule is less then the volume of the interior of the capsule so that an upper surface of the liquid is formed in the entire surface of which is viewable through the transparent capsule.

Abstract: A vial having an outer wall which is straight and cylindrical and a curved inner cavity. The inner cavity is curved in a substantially uniform arc. The apex of the curved cavity is closer to the cylindrical outer wall of the vial than the ends of the inner cavity. The inner cavity is substantially uniform in cross section throughout its length.

Abstract: A level system for accurately and efficiently providing a levelness measurement. The level system includes a container positionable within a frame structure for retaining a volume of liquid, a upper compartment within an upper portion of the container for retaining a buoyant member, a first paddle and a second paddle pivotally attached within the container about the buoyant member, and an indicator member attached to the paddles for indicating a levelness or plumbness of a structure. As the buoyant member moves within the upper compartment, the paddles move the indicator member accordingly.

Abstract: A vial having an outer wall which is straight and cylindrical and a curved inner cavity. The inner cavity is curved in substantially uniform arc. The apex of the curved cavity is closer to the cylindrical outer wall of the vial than the ends of the inner cavity. The inner cavity is substantially uniform in cross section throughout its length.

Abstract: An aid apparatus for level surveying instrument comprises a housing having a receiving chamber therein, two channels at opposite ends of the receiving chamber respectively, a window at one side of the receiving chamber, and a socket opening at the side wall of the housing connecting to receiving chamber via the channel. A controlling member is slidable received in the housing. The controlling member has a movable bar, two seal block disposed at opposite ends of the movable bar for sealing the channel, and a driving member is provided at the housing for driving the controlling to shift, whereby the sealing block being driven by the driving member to seal the channel and to depart from the channel to prevent bubbles formed in liquid.

Abstract: A spirit level having a sub-assembly on the body. The sub-assembly has a vial holder having two spaced pockets. A curved vial having two ends received in the pockets and resilient ribs having a curve matched to the vial and engaging the vial to hold the vial in an adjusted position. Each vial can be adjusted relative to a separate vial holder and each vial holder/vial sub-assembly can be independently adjusted and set relative to an appropriate edge of the level. The vial snaps into a fixed receptacle on either side of the vial holder. One side of the holder is curved to match the curve of the vial to insure that the vial is properly positioned. The underside of the vial holder may be relieved to increase flexibility to make it easier to snap the vial into place.

Abstract: An instrument for use in alignment, plumb and leveling functions includes a laser diode projecting a beam through a liquid contained in a vessel. Floating in the liquid is a compensator float which includes telescope optics so as to diminish the angle of rays leaving the telescope as compared to rays entering the telescope. The laser beam passes through the liquid and through the telescope, exiting from a window at the top or side of the instrument. By selecting the proper relationship between the telescope's magnification and the index of refraction of the liquid, the instrument is made to correct for small tilt angles of its housing. Various embodiments are disclosed for projecting upward or downward plumb beams, level beams or both.

Abstract: An inclinometer comprising a housing having transparent front plate and flat bottom, a gravitated rotational protractor having angle graduation printed on the front panel, a pendulum swing needle and protractor rotation locking device. By controlling the locking device, the protractor can be released to rotate freely and can be locked in a position. When the protracted is unlocked, the pendulum swing needle and the gravitated rotational protractor will always rotate to the relatively same position (the needle point to "0" degree angle). Then the locking device can lock the protractor to prevent rotation and the needle continues to rotate to measure the angle to which the inclinometer has been tilted.

Abstract: An automatic inclination corrector and an inclination sensor using the automatic inclination corrector free from the temperature, for optical instruments. A transparent container 3 seals silicon oil C having a free liquid surface C1. A collimation lens 2 guides the laser beam from the diode 1 to the free liquid surface C1. The inclination corrector corrects the tilt of the instrument to glide the laser beam L4 from the container 3 to advance the beam upward with a normal angle. A reflecting mirror 5 reflects beam L2 after total reflection at the free liquid surface C1. The beam is inverted by a roof prism 6 and passes through silicon oil C and the free liquid surface C1 once. This removes the refractive index n influence to the laser beam L4, and gives an angular change to the laser beam 4 to head the laser beam L4 to a fixed direction.

Abstract: A pocket level provided with magnet includes a housing having a sight opening formed therein. A liquid level indicator, in the form of a bubble vial having a pair of closed end walls, is slidably received within the open end portion of the housing and is observable through the sight opening. At least one of the closed end walls of the liquid level indicator is engageable with the housing. A cap is slidably inserted into the open end portion of the housing and a clip which is adapted to hold the level in one's pocket is secured thereto.

Abstract: A position sensor comprises two curved surfaces concentrically aligned to form a container which is filled with a viscous fluid and a bubble of a lighter-weight fluid and placed between a radiation source and a radiation detector. The bubble changes position within the container when the sensor is moved, transmitting a beam of radiation from the radiation source through the bubble to activate a section of the radiation detector while the remainder of the radiation is blocked by the fluid. Position sensing circuitry translates a signal from the activated section of the radiation detector into position coordinates for point in space corresponding to the position of the bubble in the container.

Abstract: A spirit level vial construction provides various refinements in the structure and method of manufacture of vials used for the containment of fluid and adapted to be installed in spirit levels. The construction is particularly adapted to use with spherical vials, i. e., level vials having a concave spherical form within the sight glass portion containing the bubble, and adapted to provide level information relative to a planar surface. However, the present construction may also be used for tubular type level vials. Vials using the present construction are formed of plastic materials (particularly acrylics) for economy, and are preferably molded by an injection molding method in order to reduce substantially any warping or deformation during the molding process. Various clear or dyed fluids which are compatible with the plastics may be used, particularly mineral spirits.

Abstract: An inclination sensor is disclosed. The sensor includes two temperature controlled inclination devices that are mounted orthogonal to each other. The inclination devices include an oven, a resistive element attached to the oven, an inclination transducer mounted in the oven and a thermistor being mounted to the oven. The thermistor produces a signal representative of the actual temperature of the oven. A microprocessor receives the actual temperature signal of each inclination device and produce heating signals to energize the corresponding resistive elements to control the temperature of the respective ovens to a desired temperature.

Abstract: A spirit level including a body portion having at least one open, hollow end, the body portion having at least one aperture formed on a face thereof, and a clamp insertable into the at least one hollow end, the clamp including at least one vial mounting portion, the clamp being folded and inserted into the at least one hollow end, the at least one vial mounting portion being adapted to be fixedly held in the at least one aperture after insertion of the clamp into the at least one hollow end, wherein a vial is fixedly mountable in the at least one vial mounting portion.

Abstract: A tube bender angle indicator is attached to the handle of a manual tube bender and has a frame to which angle indicia are applied which define an apex through which a pointer is pivotally connected to the frame. A bubble level vial is secured to the pointer so as to indicate that the bend angle has been achieved which the pointer is pointing at when the bubble is in its horizontal reference position.

Abstract: A vial for a builder's level includes a body with an interior wall and a body cavity containing a bubble. A marker ring is exposed in the cavity. In the improvement, the ring is embedded in the body and the interior wall and the ring have surfaces machined and coextensive with one another. The bubble moves smoothly across the machined wall and ring surfaces. A new method for making a level vial includes providing an intermediate vial product with a body wall having at least one marker ring embedded in it and machining the wall and the ring to form a wall surface free of discontinuities. The intermediate vial product is also disclosed.

Abstract: A tilt angle automatic compensator used for a device requiring verticality or horizontality is disclosed. The automatic compensator comprises a container 4 where a transparent liquid to form free liquid surface 1 is sealed, a light projection system for projecting light beam toward the free liquid surface at a predetermined angle so that it is totally reflected on the free liquid surface, and an optical system arranged at a predetermined position along optical path of the totally reflected light beam after passing through the container with sealed liquid and for equalizing change of reflection angle of optical axis corresponding to change of incident angle of optical axis in all directions. When the liquid container is tilted and incident angle of the light beam is relatively changed with respect to the free liquid surface, sensitivity varying according to the direction of change of reflection angle is optically compensated.

Abstract: A golf ball position marker has a thin, circular body that is sufficiently transparent to permit viewing 1) of a body-defined, disc-shaped, oil-filled chamber, 2) of body-carried indicia located adjacent the chamber, and 3) of a steel ball that is movably housed within the chamber and that cooperates with the indicia to provide an indication of the slope and break of a portion of a golf green on which the marker is placed. The movable ball and the indicia cooperate 1) to indicate that a portion of a golf green on which the marker is positioned is "level" if the ball remains centered within the chamber, 2) to indicate the direction of slope of an inclined green by the direction in which gravity causes the ball to move from the center of the chamber when the marker is placed on an inclined green, and 3) to indicate steepness of slope of an inclined green by the speed with which the ball moves from the center to one side of the chamber when the marker is placed on an inclined green.

Abstract: A leveling device is provided that has a hollow thin rectangular housing and is constructed of transparent plastic. The housing holds two different types of fluids, such as oil and water, or a mix of air and fluid. The two immiscible fluids allow the device to be used as a level which operates when the line between the fluids aligns with a datum line that is etched or marked upon the surface of the transparent housing. The device can be attached to an article to be leveled by an adhesive back on the leveling device or alternatively by thumb tacks inserted through holes provided in the housing of the device. The relatively long line between fluids allows the device to be used in judging the degree to which the article is non-level relative to its environment, and also allows the device to hang an article at a specific angle relative to a wall, floor or ceiling. A version of the level can be constructed with a flexible and bendable housing to allow the level to be used to align objects of any shape.

Abstract: The present invention provides a locator/monitor capable of locating a boring tool and monitoring the progress of the tool for control purposes. The locator/monitor may be used in expedited locating methodology and straightforward calibration techniques of the present invention. A durable and cost effective pitch sensor is also provided by the present invention. In addition, the present invention provides a slotted transmitter housing formed of an electrically conductive material, where the magnetic field generated by the transmitter is capable of penetrating to the surface.

Abstract: A device utilized for accurately measuring inclination angles independent of roll position using optical methods, whereby an amplitude of reflected (or refracted) light rays from a surface of a gravity-leveled liquid are detected by a photo-detector. The amplitude of the detected light beam is a function of the beam's angle of incidence to the liquid, which is proportional to the angle of the sensor's inclination. The incline sensor includes a cylindrical symmetric vessel which is partially filled with a liquid, an axially symmetric light emitting diode (LED) and a photo-detector. The fluid is chosen to have indices of refraction of at least 1.33, or reflectivity >0.60 so that measurable refraction (or reflection) angles can be realized for the geometry of the sensor. The liquid is also chosen to have freezing and boiling points acceptable for use in the desired applications.

Abstract: A very small pitch sensor which accurately measures angular rotation about he pitch axis while being substantially insensitive to angular rotations about the roll or yaw axes. The pitch sensor comprises a spherical cavity that is fluid filled. The fluid fill further comprises one half conductive fluid and one half dielectric fluid. The fluids are selected to be immiscible and of different densities. The inside of the spherical cavity is segmented into three surface areas for connection to an electronic circuit. The electronic circuit measures voltage differentials between the segmented surface areas which vary with the conductive fluid surface in contact with the respective segmented areas. The conductive fluid surface contact area varies with the angular rotation of the cavity and about the pitch axis.

Abstract: An inclination angle metering apparatus is arranged such that a beam from a light source is split into two beams by a half-mirror provided in a light path between the light source and the surface of a liquid. One beam is reflected by the liquid surface falls on a line sensor, and the other beam falls on the line sensor without reflected by the liquid surface. When a housing and the liquid are relatively inclined, an incident position of one beam changes on the line sensor, whereas an incident position of the other beam does not change. An inclination angle to the liquid surface is determined based on the incident position of one beam with respect to the incident position of the other beam.

Abstract: An integral angle measurement device employs a printed circuit board having electronic components mounted on the front surface thereof and having a pair of sensor plates etched into the back surface thereof. Containment of the sensor fluid adjacent the sensor plates is accomplished by soldering a sensor cover to an etched sealing ring on the back of the circuit board. The sensor plates etched into the back of the printed circuit board, in combination with the sensor fluid, act as variable resistors whose resistance changes as a function of their angle of rotation from a reference position. An output signal across these variable resistors is in or out of phase with an applied reference signal. The output signal is demodulated with the same reference signal and then filtered to a DC level that corresponds to the angle of rotation. An output stage serves as a driver and also as a means for permitting the user to remotely control the electronic gain of the angle measurement device.

Abstract: A two-axis inclinometer having an inclination-sensitive ray-deflecting device is described, via which a geometrical figure having at least one angle is projected onto a linear array. In addition to providing high resolution, a large measurement range is also opened up by the special arrangement and configuration of the geometrical figure. X-, Y- and overlapping inclinations can be determined simultaneously using the described inclinometer.

Abstract: A sensor (10) for measurement of acceleration and/or tilt of a movable object, particularly a motor vehicle, features an interior space (12) partially filled with fluid (15). Within that space, at least two heatable, temperature-sensitive electrical circuit elements are arranged so that, in a rest or initial position of the sensor, they are equally covered or wetted by the fluid. If the acceleration and tilt of the movable object are both zero, or the two cancel each other out, the sensor reading is zero. If this is not the case, the acceleration or tilt leads to a differing degree of coverage or wetting of the at least two circuit elements, and thus to a non-zero sensor reading.

Abstract: An improved hand tool comprising a generally L-shaped frame having two legs each formed with a pair of channels spaced apart by a central ridge, and having panels of transparent material, such as tempered glass or plastic, mounted in the channels with a quantity of a suitable liquid contained between the panels to define a level-indicating chamber extending substantially the entire length of each leg and having indicia positioned adjacent the ends of each of these chambers to provide information relating to incremental discrepancies.

Abstract: A multi-axis, multi-purpose sensor for use with implantable medical devices, and for simultaneously detecting the patient's posture and activity level. The sensor includes a hermetically sealed, fluid-tight, bio-compatible housing. The housing is formed of a plurality of adjacently secured sides, and a plurality of side electrodes coupled to the sides. A central electrode is disposed at the geometric center of symmetry of the housing, to allow measurement of voltage changes between the central electrode and the side electrodes. A non-toxic electrically conductive electrolyte fills about half the housing, and immerses part of the central electrode and the side electrodes. The sensor further includes a low frequency bandpass filter for passing low frequency signals indicative of the patient's posture, and a high frequency bandpass filter for passing high frequency signals indicative of the patient's activity.

Abstract: A sensor for an inclination measuring device which comprises a capsule (3) part-filled with a conductive liquid. First to fourth electrodes (A-D) are disposed within the capsule in contact with the liquid. An electrical signal is applied between electrodes (C, D) and one then the other of electrodes (A, B), to derive a signal indicative of the degree of immersion of the electrode (A), and then the electrode (B) within the liquid. The ratio of these signals is related to the angle of inclination of the capsule about the reference axis O and relative to a first reference angle defined at the gap between the electrodes (A, B). A similar gap, defining a second reference angle is disposed between electrodes (C, D), perpendicular to the gap between electrodes (A, B), and by reconfiguring the electrodes (A-D), to measure the degree of immersion of electrodes (C and D), the sensor is able to sense any angle of inclination about the reference axis.

Abstract: A sensor for an incination measuring device which comprises a capsule (3) part-filled with a conductive liquid. First to fourth electrodes (A-D) are disposed within the capsule in contact with the liquid. An electrical signal is applied between electrodes (C, D) and one then the other of electrodes (A, B), to derive a signal indicative of the degree of immersion of the electrode (A), and then the electrode (B) within the liquid. The ratio of these signals is related to the angle of inclination of the capsule about the reference axis (O) and relative to a first reference angle defined at the gap between the electrodes (A, B). The capsule (1) is also constructed to compensate for thermal effects, by forming the sides of the capsule so that they are responsive to pressure change within the capsule caused by thermal expansion of the contents of the capsule to expand the volume of the capsule, to keep the level of liquid therein constant.

Abstract: A leveling apparatus includes at least two scales defined by enclosed receptacles, each having a cavity and a port into the cavity. Each receptacle also preferably has a top wall with a convex inner surface defining the top of the cavity. The top wall also preferably has a concave outer surface. The receptacles are connected through their ports in a common closed fluid communication system which is preferably only partially filled with a liquid sensitive to the levelness of a surface to be tested. The apparatus is spread across a surface whose levelness is to be tested, and the levelness is indicated by the relationships between the surfaces of the liquid in the scales and elevation indicating indicia on the scales as observed through the preferably concave top wall of each receptacle.

Abstract: A device measures or controls a change of a level or a variation in a change of a level between several points. The device includes closed vessels (2) placed respectively at each of the points. The vessels are partially filled with a liquid (53) and are connected by liquid pipes emerging in their lower portion so as to form a liquid circuit (31) and by gas pipes emerging in their upper portion so as to form a gas circuit (36). Each vessel is equipped with a capacitive proximity sensor (11) placed above and at a distance from the upper surface (54) of the liquid which it contains and which provides a signal with respect to position in the vertical direction of a zone of the upper surface of the liquid in the vessel. A device comprises the signals provided by the sensors so as to be able to provide data with respect to the vertical position of the vessels and, consequently, with respect to the points relative to one another or relative to a reference vertical position.

Abstract: A capacitive type, multi-electrode inclination sensor device utilizes a conductive fluid acting as a common capacitive electrode contained within a cylindrical cavity. Two or more coplanar sensor electrodes are covered by a thin dielectric film and are mounted on an end wall of the cavity. Each insulated electrode forms one plate of a capacitive element with the conductive fluid forming the other plate. The geometry of the sensor electrodes is such that for a given physical position of the device (such as level or plumb), equal conductive fluid coverage of a given pair of sensor electrodes occurs, yielding two identical value capacitances. Any inclination of the device within the plane of the capacitive plates then increases one capacitance's value while decreasing the other, with the differential change in capacitance being proportional to the angle of inclination.

Abstract: An instrument for measuring angles, vertical line or horizontal line includes a square casing having two axial lines crossing at a center of the casing and having a colored liquid filled in the casing, and a rotating disc rotatably mounted on the casing, in which the rotating disc is formed with an upper half circle portion radially formed with a plurality of angular graduations in terms of degrees, and formed with a lower half circle portion having two vertical columns parallelly formed below a diametrical line dividing the two half circle portions, and at least a reference line linked between any two horizontal graduations respectively formed in the two vertical columns, whereby upon a rotation of the disc to parallel the reference line to a liquid level of the colored liquid, an angle can be obtained by matching the angular graduation with any one axial line when the casing is laid on or coincided with a plane to be measured.

Abstract: A flap holster with the flap pivotally and removably secured to either side of an ambidextrious holster. The holster inlcudes an opening for the insertion and removal of a handgun and a transverse slot below the opening on each side. The flap is pivotally connected to one side of the holster and extends over the handgun opening. On the underside of the flap, an extensible strip is secured at one end to the flap and includes an end hook at the opposite end to engage one of the transverse slots and secure the flap in place. The extensible strap is preferably captured in a fabric tunnel in the underside of the flap. An inextensible flexible strap is secured at both ends to the extensible strap to limit its extension length to avoid over stressing its elastic properties. The hook is preferably a reverse directed tab dimensioned to slip into the transverse slot allowing the elasticity of the extensible strip to hold the flap closed.