Abstract: An expandable level that is configured to extend from a first length to a second length in order to identify a vertical or horizontal plane across a greater distance. The level of the present invention includes a body wherein the body has a first portion and a second portion. The first portion and second portion are axially aligned and secured together in the first position of the level with a fastener. The first portion and second portion of the body have telescoping support members operably coupled therebetween. The telescoping support members include a plurality of segments that facilitate the expansion of the length of the level wherein the first portion and second portion are moved away from each other. Sight windows and level bubbles are in both the first portion and second portion.

Abstract: Embodiments of this application provide a blockchain-based information processing method, including: obtaining an original index information set, the original index information set comprising at least one piece of original index information, each piece of original index information comprising plaintext sensitive content; obtaining information in to-be-matched blocks in a blockchain system, the information comprising information content and an information index, the information content having a correspondence with the information index; matching the information content in the information by using the original index information set, to obtain a matching result; and determining a variant index information set when the matching result indicates that the matching succeeds, the variant index information set comprising at least one piece of variant index information, the variant index information comprising the information index corresponding to the information content in the information.

Abstract: A device includes a ruler, a leveling device attached to the ruler and a plurality of pins. The device only requires one person to hang level pictures, paintings, frames and other wall hanging objects. The ruler is a made from a rigid material and has a plurality of holes therein where the pins are inserted. The ruler has a fixed length or has a telescopic structure. The plurality of holes formed in the ruler are spaced apart from one another and the spacing is uniform or variable spacing. The leveling device is a bubble leveler including three bubble levels where one bubble level is horizontally positioned, another bubble level is vertically positioned, and the third bubble level has an angle relative to the horizontally positioned bubble level. The plurality of pins include a threaded pointed screw with a knob attached to one end of the screw.

Abstract: Detailed herein is a level device having a body having a first face, an opposing second face, and a perimeter extending between the first and second faces. The perimeter includes first, second, third, and fourth sides, where a first reference surface extends along the third side and a second reference surface extends along the fourth side orthogonal to the first reference surface. A third reference surface may be between the first and second reference surfaces disposed at a 45-degree angle relative to each of the first and second reference surfaces. A first bubble vial having a first longitudinal axis parallel to the first reference surface is received in a first recess defined along the first side, and a second bubble vial having a second longitudinal axis parallel to the second reference surface is received in a second recess defined along the second side.

Abstract: Devices, systems and methods for hanging one or more objects, such as frames, on a surface. A marking device for marking a surface for hanging one or more objects. The marking device can have a main body portion having first and second arms pivotably attached thereto. The first and second arms, as well as the main body, can each have a marker to mark a target surface. The marking device can optionally have a level indicator and the first and second arms can have markers which can slide along a ruled measure for convenient positioning of marks on the target surface. Optionally, the markers can have biased, retractable, or sheathed marker pins.

Abstract: An alignment device for aligning a pair of substrates includes a second bar rotationally engaged by a first terminus to a second end of a first bar. A spirit level engaged to a first end of the first bar extends bidirectionally therefrom. A fastener rotationally engaged to the first and second bars is positioned to selectively fix the first bar relative to the second bar. With the second bar positioned on a mating surface of a first substrate, a user can rotate the first bar relative to the second bar so that the spirit level indicates horizontal and then engage the fastener. Upon positioning the second bar on a mating face of a second substrate, the user is positioned to orient the second substrate so that the spirit level indicates horizontal, wherein the mating face of the second substrate is aligned with the mating surface of the first substrate.

Abstract: A template that includes a support structure pivotably mounted to a guide, wherein the guide includes a compass with angle markings, a first guide member extending from the vertex of the compass, a second guide member extending from the vertex of the compass. In another embodiment, a medical imaging system can include a medical imaging machine with a display screen, a support structure affixed to the medical imaging machine, and a guide pivotably mounted to the support structure. A method of aligning medical implants with anatomical structures includes positioning a template over the display screen, and comparing an angle of a medical tool or implant relative to the anatomical structure of the patient to a reference angle on the guide and installing the implant in the patient at the angle indicated by the guide.

Abstract: A length selectable spirit level and measurement device for simultaneous measurement and leveling includes a first bar and a second bar. The first bar has a channel positioned therethrough, which extends between opposed ends thereof. A pair of slats positioned in the channel is slidably engaged to the first bar and thus selectively extensible therefrom. Respective indicia of a plurality of indicia coupled to the slats are alignable with a pair of points to measures a distance between the points. The second bar has a set of orifices positioned therethrough, each of which has a spirit bubble tube positioned therein and coupled to the second bar. The spirit bubble tube indicates an orientation of a longitudinal axis of the second bar relative to horizontal. The first bar is selectively engageable to the second bar so that the slats are selectively extensible in parallel with the longitudinal axis.

Abstract: Systems, devices and methods are provided for converting artwork or photographs into audio-enhanced exhibits. In particular, the embodiments disclosed herein can avoid the inconvenience and risk of damage associated with having to remove a panel on which a piece of artwork, photograph or print is mounted to power on/off or plug in an audio system. In some embodiments, an input module is provided on an edge perpendicular to the panel frame. A charging port and/or power switch are positioned perpendicular to the frame so that either can be accessed from a side edge of the panel.

Abstract: Techniques are provided for operating non-volatile storage. Peak current consumption may be reduced in connection with sensing non-volatile memory cells. Peak current consumption may be reduced when a first read condition is present. In one aspect, the value of a parameter of a voltage that is applied to a word line during a pre-read phase of a sense operation is controlled in order to reduce peak current consumption when the first read condition is present. Examples of the parameter include a ramp rate, a number of intermediate voltage levels, and a start time.

Abstract: Systems, devices and methods are provided for converting artwork or photographs into audio-enhanced exhibits. In particular, the embodiments disclosed herein can avoid the inconvenience and risk of damage associated with having to remove a panel on which a piece of artwork, photograph or print is mounted to power on/off or plug in an audio system. In some embodiments, an input module is provided on an edge perpendicular to the panel frame. A charging port and/or power switch are positioned perpendicular to the frame so that either can be accessed from a side edge of the panel.

Abstract: A level including a first plate defining a top surface of the tool, and a second plate defining a bottom surface of the tool. The bottom plate extends generally parallel to the first plate. The level also includes a center plate having two opposing side surfaces extending generally perpendicular to the first plate and the second plate. The center plate connects the first plate and the second plate. The level further includes a plurality of apertures extending through the center plate, and a plurality of tubular vials disposed within the plurality of apertures. Each tubular vial contains fluid and air. The level also includes a slot extending along the first plate from a first end of the tool to a second end of the tool. The slot is configured to receive a straight edge.

Abstract: Devices, systems and methods for hanging one or more objects, such as frames, on a surface. A marking device for marking a surface for hanging one or more objects. The marking device can have a main body portion having first and second arms pivotably attached thereto. The first and second arms, as well as the main body, can each have a marker to mark a target surface. The marking device can optionally have a level indicator and the first and second arms can have markers which can slide along a ruled measure for convenient positioning of marks on the target surface. Optionally, the markers can have biased, retractable, or sheathed marker pins.

Abstract: A tool shaped in a U-shape for accepting a standard U strut. The tool has opening for marking the strut for cutting purposes and hole openings for marking the center of standard struts.

Abstract: A tool for locating a proper position for a portal incision for hip arthroplasty, the tool having at least one generally elongated body defining an axis, the generally elongated body having a slot at one end, the slot being angled at an approximately 45 degree angle relative to the axis of the generally elongated body, the slot configured to receive a cutting member or guide tool. A second generally elongated body may be connected to the first generally elongated body to form a right angle. If the lengths of the two generally elongated bodies are substantially equivalent, then when the second generally elongated body is inserted into the acetabulum, the first generally elongated body positions the slot in the proper location such that sliding a guide tool or cutting member through the slot allows a portal incision to be created in the proper location. In some embodiments, the generally elongated bodies may have adjustable lengths.

Abstract: A golf device including a first elongated portion. The golf device may include a second elongated portion. The golf device may include an arch portion slideably engageable inside the first elongated portion and the second elongated portion.

Abstract: A golf device including a first elongated portion. The golf device may include a second elongated portion. The golf device may include an arch portion slideably engageable inside the first elongated portion and the second elongated portion.

Abstract: An adjustable picture frame tool comprising a longitudinal device for housing slidable members at each end wherein the slidable members have the ability to expand and contract in length at both ends of the longitudinal device is disclosed. The longitudinal device and end slidable members each defines a plurality of center spaced holes along their longitudinal axis, respectively. In one preferred embodiment the holes are spaced a mm apart from each other. A clickable circular locking button is located in the middle of the longitudinal device that allows the slidable members to be locked in place to the longitudinal device. In use, a simple click or push of the center button locks the slidable members relative to the longitudinal device wherein a second click of the button and the slidable members can move either outwards or inwards.

Abstract: A level including a first plate defining a top surface of the tool, and a second plate defining a bottom surface of the tool. The bottom plate extends generally parallel to the first plate. The level also includes a center plate having two opposing side surfaces extending generally perpendicular to the first plate and the second plate. The center plate connects the first plate and the second plate. The level further includes a plurality of apertures extending through the center plate, and a plurality of tubular vials disposed within the plurality of apertures. Each tubular vial contains fluid and air. The level also includes a slot extending along the first plate from a first end of the tool to a second end of the tool. The slot is configured to receive a straight edge.

Abstract: The present invention is directed generally to tools that are lightweight, high quality, durable, rigid and strong. For example, various tools used to level items and/or as a straight edge for aligning or drawing lines on items may be designed in an improved or augmented beam style so that they are lightweight, strong, durable and rigid so as to hold their shape under stress or return to their original shape after being stressed. In various exemplary embodiments, the beam style level and/or straight edge may have a first main elongated side to which two elongated perpendicular sides are connected or coupled. At least one or more higher strength elongated sides, for example a second elongate side, may be comprised of a closed or triangular shaped side. For example, the second elongated side may be, for example, a triangular shaped construction.

Abstract: A conduit-bending level has a pair of bubble levels oriented in such a manner as to facilitate the bending of conduit in a first plane and a second plane that is perpendicular to the first plane. This bending operation is preferably conducted without having to detach the conduit-bending level from the conduit in order to make the second bend.

Abstract: The present invention is directed generally to tools that are lightweight, high quality, durable, rigid and strong. For example, various tools used to level items and/or as a straight edge for aligning or drawing lines on items may be designed in an improved or augmented I beam style so that they are lightweight, strong, durable and rigid so as to hold their shape under stress or return to their original shape after being stressed. In various exemplary embodiments, the I beam style level and/or straight edge may have a first main elongated side to which two elongated perpendicular sides are connected or coupled. At least one or more higher strength elongated sides, for example a second elongate side, may be comprised of a closed or box shaped side. For example, the second elongated side may be, for example, a box shaped construction.

Abstract: The disclosure proceeds from a system with a measurement bar and a measurement device, having at least one computation unit, an inclination measurement means and an electronic distance measurement means. The disclosure proposes that the system have a coupling apparatus which is provided for coupling the measurement bar and the measurement device such that they can be separated by an operator.

Abstract: A lighted level tool comprising a body including at least one vial opening, a vial disposed at least partially within the at least one vial opening, a light source for illuminating the vial, an insert member mounted at a predetermined location in the body relative to the at least one vial opening, and at least one an end cap mounted at an end of the body. The insert member is configured to receive the vial therein and to hold the light source opposite an end of the vial. A control circuit for powering the light source is mounted in the at least one end cap.

Abstract: A level includes a body comprising a first portion having a first reference surface, and a second portion having a second reference surface, the second reference surface being spaced from the first reference surface. The body also includes an intermediate member comprising a wall positioned between the first and second portions, the wall being generally perpendicular to at least one of the reference surfaces. The level also includes an orientation indicator coupled to the intermediate member, the orientation indicator being positioned to indicate an orientation of at least one of the first and the second reference surfaces. The level additionally includes an indicator support configured to support the orientation indicator, and a resilient member positioned between the orientation indicator and the indicator support. A compression the resilient member facilitates a calibration of the orientation indicator, while the indicator support supports the resilient member and engages opposite sides of the wall.

Abstract: A multi-purpose measurement apparatus having a combination spirit level and a protractor, for precise measurement of orientation and angle of a material, the apparatus having a frame for resting against the material, said frame having a strip of ruler markings at the bottom portion of the face of the frame and the bottom portion of the rear of the frame, said frame further having a slot at a substantially centermost position of the frame; a clear, global housing, forming front and rear windows on the frame and in the slot at the substantially centermost position of the frame, the housing filled with an oil composition.

Abstract: A level including an elongate hollow frame with two sidewalls and a topwall extending therebetween. A topnotch is formed by removal of a topwall section and adjacent sections of sidewalls including notch-defining bottom and side edges. A central vial is within the topnotch. The frame includes an inner horizontal wall extending between the sidewalls at the notch-defining bottom edges. A central-vial reference surface is formed in the inner horizontal wall parallel to the top and bottom measuring surfaces and defining a notch-bottom. The central vial is supported against the central-vial reference surface in accurate orientation without calibration. The central vial is secured with respect to the inner horizontal wall by mechanical fasteners. The frame further preferably includes an integral inner vertical wall extending between the top and bottom walls thereby reinforcing the frame along the frame length.

Abstract: A spirit level including a profiled body with a bottom wall including a first outer measurement surface, a head wall facing this bottom wall, a second outer surface in sections parallel to the measurement surface, and side walls connecting the bottom wall to the head wall, and presenting a first or second outer lateral face. The body includes a bubble vial body. The body presents an asymmetric design on the lateral face over the length of the profiled body, where a first lateral face viewed in the longitudinal direction of the profiled body, presents a channel-shaped course, and a facing second lateral face includes a first section which runs on the head side and has a convex course, and a subsequent second section, whose separation from the vertical axis of the profiled body increases starting from the first section in the direction of the measurement surface.

Abstract: A level for indicating the orientation of a surface includes a first planar surface, a second planar surface, and a web coupled to the first planar surface and the second planar surface such that the first planar surface is spaced apart from and is parallel to the second planar surface. A vial defines a long axis and contains a liquid and a gas bubble. The vial is coupled to the web such that the long axis is substantially parallel to the first planar surface. A tube deburring portion is coupled to the web and includes a male conical portion arranged to deburr an inner edge of a tube and a female conical portion arranged to deburr an outer edge of the tube.

Abstract: A hands-free measuring instrument is disclosed. The disclosed instrument includes an upright member extending perpendicularly from a base member. At least one magnet is affixed to the instrument to facilitate the mounting thereof on a ferrous workpiece. The disclosed instrument includes at least one level disposed thereupon. Graduations may be provided on the instrument to facilitate measurement of linear distances. Embodiments are disclosed wherein an adjustable ruler arm is provided to facilitate the measurement and inscribing of arbitrary angles relative to the upright member.

Abstract: The present invention is directed generally to tools that are lightweight, high quality, durable, rigid and strong. For example, various tools used to level items and/or as a straight edge for aligning or drawing lines on items may be designed in an improved or augmented I beam style so that they are lightweight, strong, durable and rigid so as to hold their shape under stress or return to their original shape after being stressed. In various exemplary embodiments, the I beam style level and/or straight edge may have a first main elongated side to which two elongated perpendicular sides are connected or coupled. At least one or more higher strength elongated sides, for example a second elongate side, may be comprised of a closed or box shaped side. For example, the second elongated side may be, for example, a box shaped construction.

Abstract: A rolling ruler comprises a blade member configured to facilitate taking a measurement. The blade member is coupled to a handle that is configured to be gripped by a user, wherein the handle acts as a housing for storing a plurality of electronic components, the plurality of electronic components providing predefined functionalities to the rolling ruler. Further at least one roller with a rolling surface that is partially exposed through a backside of the handle for contacting a surface to be measured is in operable contact with a portion of the plurality of electronic components to facilitate measuring distance based on rotations of the at least one roller.

Abstract: A levels of the type including an elongate hollow frame and a magnet secured to the frame having a magnet-mounting structure which includes first and second magnet-holding members positioning the magnet with respect to a bottom-wall opening. The first magnet-holding member has a first side flange; and the second magnet-holding member has a second side flange. Each side flange is positioned to extend along one of opposite frame sidewalls at an inner surface of a frame bottom wall. A locking member pulls the magnet-holding members together such that the side flanges are locked inside the level frame along the opposite sidewalls, thereby mechanically securing the magnet to the level frame.

Abstract: A level including an elongate hollow frame with two sidewalls and a topwall extending therebetween. A topnotch is formed by removal of a topwall section and adjacent sections of sidewalls including notch-defining bottom and side edges. A central vial is within the topnotch. The frame includes an inner horizontal wall extending between the sidewalls at the notch-defining bottom edges. A central-vial reference surface is formed in the inner horizontal wall parallel to the top and bottom measuring surfaces and defining a notch-bottom. The central vial is supported against the central-vial reference surface in accurate orientation without calibration. The central vial is secured with respect to the inner horizontal wall by mechanical fasteners. The frame further preferably includes an integral inner vertical wall extending between the top and bottom walls thereby reinforcing the frame along the frame length.

Abstract: A level for indicating the orientation of each of a surface, a first electrical device, or a second electrical device, the level including a first planar surface, a second planar surface, a web, and a vial. The web is coupled to the first planar surface and the second planar surface such that the first planar surface is spaced apart from and is parallel to the second planar surface. The vial has a long axis and contains a liquid and a gas bubble and is coupled to the web such that the long axis is substantially parallel to the first planar surface. A first perimeter is formed as part of the web, shaped substantially the same as a portion of the first electrical device, and sized to engage the portion of the first electrical device such that the vial is operable to indicate the orientation of the first electrical device.

Abstract: A level including an elongate hollow frame with two sidewalls and a topwall extending therebetween. A central vial is within a topnotch formed by removal of a topwall section and adjacent sections of sidewalls including notch-defining bottom and side edges. An integral inner vertical wall extends between the top and bottom walls thereby reinforcing the frame along the frame length. The inventive level further preferably includes an external brace reinforcing a central frame portion weakened by forming the topnotch. The external brace includes first and second plate members each against one of the sidewalls about the notch-defining bottom and side edges and each substantially spanning a respective one of the sidewalls. A fastening member extending through the sidewalls and pulling the plate members toward each other to sandwich the sidewalls therebetween, thereby reinforcing a central frame portion weakened by forming the topnotch.

Abstract: A level including an elongate hollow frame with two sidewalls and a topwall extending therebetween. A central vial is within a topnotch formed by removal of a topwall section and adjacent sections of sidewalls including notch-defining bottom and side edges. The frame includes an inner horizontal wall extending between the sidewalls at the notch-defining bottom edges. The central vial is supported in accurate orientation without calibration against a cental-vial reference surface formed in the inner horizontal wall parallel to the top and bottom measuring surfaces and defining a notch-bottom. An integral inner vertical wall extends between the top and bottom walls thereby reinforcing the frame along the frame length. A plumb-vial structure has a viewing-end region and an opposite-end region. The viewing-end region includes an elongate ramp sloping along a level-longitudinal axis toward the plumb vial with an inclination permitting vial viewing from shallow angles.

Abstract: A screw mount placement device uses a gear assembly mounted in a housing to allow an item to be hung levelly and further allow the item to be hung in a desired position relative to at least one other already mounted object.

Abstract: A multi-tool assembly with retractable tape measure, collapsible right angle square, straight edge arm with built-in razor blade knife and protractor, complete with a set of three retractable screwdrivers, all mounted in a single, compact, housing assembly. The combination; straight edge arm and razor blade knife, locks into one of several positions; to stay closed, to form into a carpenter's square and to extend the razor blade knife. The arm can be manually opened or spring powered to snap open like a switchblade when the release button is activated. The thin razor blade cutting edge creates a knife that is much sharper than ordinary pocket knives. The set of screwdrivers are permanently mounted within the back of the housing assembly. Each of the screwdrivers can be pivoted open to protrude out from the back of the housing assembly, allowing each screwdriver to be used individually.

Abstract: The present invention relates to a picture hanging, positioning and leveling device for use in marking one or more points on a wall or other vertical surface where fastener devices should be installed in order to precisely hang one or more pictures or other objects at their desired locations on the wall. The device includes an elongate frame component which, in one embodiment, may be a carpenter's level-like apparatus, one or more first extension components extending up from the elongate frame and one or more second extension components extending out from the first extension component in a plane parallel with the face of the elongate frame. Each second extension component in configured to include at one end both a hook element for insertion into hanging elements on the back of the objects to be hung and a marking element for marking a point on the wall for the subsequent installation of a fastener device.

Abstract: The present invention relates generally to a sliding square that can be slipped over a standard retractable tape measure that is extendable perpendicularly to abutment wall allowing 0-90 degrees angle lines to be scribed at measured distances from the end of a work piece. Sliding Square also may include a depth gage, bubble levels on the x and y planes, a protractor scale along with linear dimensions along its right angle straight edge side and standard rafter pitch angles to be defined. Abutment wall t's into base 32 extending equally above and below base so that it functions right side up from the left side of a work piece or flipped over from the right side.

Abstract: A device for three-dimensional representation of horsebacks through measurement points, comprising: plural vertically telescoping and column shaped segments which are connected with a frame and which include flexible transversal elements at their upper end which flexible transversal elements are bent like an umbrella and have flexible curvatures, wherein the vertical segments are configured to be variably offset from one another in the frame and configured fixable in a temporary manner and the curvature of the transversal elements that are bent in the shape of an umbrella is adjustable and fixable in a temporary manner, wherein the transversal elements include measuring points which are configured variably arrangeable in a vertical plane through devices for adjusting the curvature of the transversal elements, and wherein the measuring points of the transversal elements are arranged in the surface of the three-dimensional contour of the horseback.

Abstract: An illuminated device for checking an orientation to horizontal, comprising an elongated flat surface for engaging a surface of an object; at least one bubble level disposed in relation to the elongated flat surface to facilitate indicating when the elongated flat surface is horizontal; a light source for illuminating a region in proximity to the elongated flat surface; and an elongated body comprising the elongated flat surface, the at least one bubble level, and the light source.

Abstract: A combination level/try square includes an elongated body with an arm at one end thereof. The arm is rotatable between a non-use position against the body and a use position in which the body and the arm define a try square. The body incorporates three indicators, namely a plumb indicator, a level indicator and a slope indicator. In a second embodiment, a laser pointer is provided on one end of the body.

Abstract: The present invention is directed generally to tools that are lightweight, high quality, durable, rigid and strong. For example, various tools used to level items and/or as a straight edge for aligning or drawing lines on items may be designed in an improved or augmented I beam style so that they are lightweight, strong, durable and rigid so as to hold their shape under stress or return to their original shape after being stressed. In various exemplary embodiments, the I beam style level and/or straight edge may have a first main elongated side to which two elongated perpendicular sides are connected or coupled. At least one or more higher strength elongated sides, for example a second elongate side, may be comprised of a closed or box shaped side. For example, the second elongated side may be, for example, a box shaped construction.

Abstract: A level 11 is provided comprising a base 1 having a top reference edge 2 and recession 3 wherein a slidable member 8 fits within the recession 3 of the base 1 and is slidable to extend the top reference edge 2 of the base for multiple lengths. Further embodiments of the present invention provide a level 11 having attachment means to level at various angles and additional lengths.

Abstract: A level of the type having an elongate hollow frame including two sidewalls each defining axially aligned vial openings into the frame. A vial casing is secured with respect to the frame and defines a hermetically sealed single-cavity casing interior entirely enclosing a liquid-and-bubble vial with a substantially cylindrical outer surface extending between two vial ends. The casing is formed of two opposite round face-walls and a surrounding cylindrical wall therebetween. The cylindrical wall has a pair of opposed major wall-portions of first thickness and a pair of opposed intervening wall-portions of second thickness greater than the first thickness. Each intervening wall-portion defines a recess which snugly receives a corresponding one of the vial ends.

Abstract: A rolling ruler comprises a blade member configured to facilitate taking a measurement. The blade member is coupled to a handle that is configured to be gripped by a user, wherein the handle acts as a housing for storing a plurality of electronic components, the plurality of electronic components providing predefined functionalities to the rolling ruler. Further at least one roller with a rolling surface that is partially exposed through a backside of the handle for contacting a surface to be measured is in operable contact with a portion of the plurality of electronic components to facilitate measuring distance based on rotations of the at least one roller.

Abstract: A hand-held level and plumb tool that includes a homogeneous, L-shaped body, a first level indicating device, and a second level indicating device. The L-shaped body has first and second legs arranged at a 90° angle. The first leg defines an interior side, an exterior side, a central panel extending between the sides, and a length in extension of the first leg from the second leg to a free end. A slot is formed through a thickness of the central panel and extends along at least a majority of the length. The first level indicating device is assembled to the central panel of the first leg at a location spaced from the slot. The second level indicating device is assembled to the second leg. One or both of the legs can include measurement-related indicia selected in accordance with staircase construction standard dimensions.

Abstract: An angle square includes a basic ruler, a pivotal ruler and a light-projecting element. The basic ruler includes a space defined therein. The pivotal ruler is pivotally connected to the basic ruler between an idle position in the space and an active position out of the space. The light-projecting element is connected to the pivotal ruler.