Abstract: A multifunctional toy for early childhood education comprises a plurality of basic elements and at least one expansion element, wherein the basic element has a rollable outer surface and an inner cavity for sleeving other basic elements, and a connector is arranged between at least two basic elements, and the connector is installed between the two basic elements in a mutually matched manner; and a plurality of steps are detachably connected on the connector, and the expansion element is detachably connected with the basic elements.

Abstract: An assemblable story and picture display may include a plurality of substrates combinable to resemble an object. The assemblable story and picture display may define an outer profile that may resemble an apple, banana, duck, egg, Christmas tree, or any other relatively simple object. Each of the plurality of substrates may define a portion of the outer profile making up the assemblable story and picture display. Each of the plurality of substrates may include a portion of a story or images wherein the story is conveyed sequentially across the plurality of substrates. The assemblable story and picture display may further include an outer decorative image or layer. The assembled story and picture display may include exterior decorative elements indicating the nature of the story depicted on each of the story or display layers.

Abstract: Assemblies combining a structure, such as a structure defined by magnetic connector pieces, with a slide assembly. In some embodiments, the slide assembly may comprise a plurality of slide pieces configured to be coupled together so as to define a slide configured to receive and direct one or more slideable pieces, such as balls, therein. The slide assembly may further comprise a plurality of slide coupling members configured to couple at least a subset of the plurality of slide pieces to the structure. The plurality of slide pieces may comprise a plurality of coupling joints configured to couple two adjacent slide pieces of the plurality of slide pieces together. Each of at least a subset of the plurality of coupling joints may be configured to be positioned at the same location in at least one dimension with respect to an adjacent structure piece upon being coupled with the structure.

Abstract: A support structure may have a base having surfaces including a top, a bottom, a front, a rear and sides. A first top slot may be formed in the top and may extend at least partially between the front and the rear. A second top slot may be formed in the top and may extend at least partially between the sides. In addition, a bottom slot may be formed in the bottom. A system for attic storage can include an attic having attic joists. A plurality of support structures, each comprising a base, may be mounted to the attic joists. At least two conventional lumber studs may be included and may extend between adjacent ones of the bases. In addition, a plurality of lumber panels may be mounted to at least one of the bases and the lumber studs.

Abstract: A building block (100) comprises a first mating portion and a second mating portion which are complementary. The first mating portion comprises a mating protrusion (140) which defines an axially extending through bore (144) and the second mating portion comprises an axially extending mating receptacle (180) which is complementary to the mating protrusion (140). The mating protrusion (140) and the mating receptacle (180) are in communication via the through bore (144), and a fastener anchoring device (146) adapted for engaging with an engagement means (920) of a fastener (900) is formed inside the through bore (144). The through bore (144) is adapted to permit axial insertion of the engagement means (920) of the fastener (900) into the mating protrusion (140).

Abstract: A modular construction toy kit includes components to construct a modular construction toy. The toy kit includes at least three contoured body sections operable to be interconnected in series with one another to cooperatively form a continuous toy body. The body sections include at least one transition body section and a pair of end body sections. Each end body section is truncated to present a contoured outer end surface that is intersected by an end joining face. The end joining faces have different marginal shapes and/or sizes. The at least one transition section presents a contoured outer transition surface and opposite, endmost transition joining faces that intersect the outer transition surface. Each endmost transition joining face marginally matches a respective one of the end joining faces to define a connection interface.

Abstract: A toy device and system includes a hollow core, segmented, vertical scaffolding or super structure adapted for manual or powered interactive manipulation of one or more multiple play stations supported on the surface of the vertical scaffolding. An integrated storage system for storing play station elements and other building and control items is mounted at the base of the vertical scaffolding. The hollow core segments of the vertical scaffolding provide a housing for selectively controllable electrical and other power sources which are subject to control by such means as a hand-held remote controller with signal receivers being mounted on the segmented super structure. The entire toy system may be disassembled and contained within the storage structures described and enclosed in a carrier device for easy transport.

Abstract: A system of blocks is configured to be compatible with each other in the construction of a columnar structure. Each block has four faces and all four faces may generally have the same dimensions. The width of the blocks may generally be about twice their height. The faces of the block also may contain a slot to add an aesthetic appearance to the column. The blocks have certain constructions features that mate with specially constructed brackets in attaching a fence panel to the completed column. The blocks have interlocking elements or projections that permit positive connection between courses of blocks. Projections of one block extend into the core another block. Adjacent blocks can be rotated 90 degrees relative to each other about a vertical axis of each block with each course. The blocks can be used to construct a column that is easy to install and structurally sound.

Abstract: A modular step stool system according to various embodiments can include a plurality of stepping blocks comprising a first stepping block and a second stepping block configured to support a user's body weight. A plurality of interlocking elements is interposed between the first stepping block and the second stepping block for horizontally and vertically interconnecting and interlocking at least the first and second stepping blocks to form a raised step platform. Some of the plurality of interlocking elements include sub-couplings which are configured to provide simultaneous horizontal and vertical interconnections. Some embodiments of the device include raised walls configured within the side walls and corner tabs inserted within the corners of the stepping blocks and configured having a profiled selected based upon the shape of the sub-couplings to facilitate stacking and interconnections in at least one of a horizontal, a vertical, a perpendicular, and an offset configuration.

Abstract: A toy vehicle, a toy assembly device and a related method includes a toy body having a plurality of component members, and a plurality of support frame members respectively supporting the component members. The component members and the support frame members have respective engaging portions that can engage and disengage in a horizontal direction. Each of the support frame members has a fitting part provided thereon for connecting the support frame members to one another. Each of the component members has a fitting portion provided thereon for connecting the components members to one another. When the support frame members, each with a component member supported thereon, are connected to one another through the fitting parts, the component members are connected to one another by the fitting portions to form the toy body, so that the toy body can engage with or disengage from the support frame members connected to one another.

Abstract: A motorized toy vehicle or Wall Racer that is capable of operating on vertical and inverted horizontal surfaces such as walls and ceilings, while being manufacturable at reasonable cost and operable on batteries having sufficient lifetime as to be enjoyable. One or more battery-powered fans draw air from around all or defined portions of the periphery of the interior volume of the Wall Racer through a carefully-shaped duct, so that the air in the portion of the duct immediately adjacent the surface flows at high velocity and low pressure; the relatively greater pressure of the surrounding air urges the vehicle against the surface, allowing it to adhere to vertical surfaces, such as walls, or operated inverted on horizontal surfaces, such as ceilings.

Abstract: A container has an open top end and a closed bottom end. A chamber is provided between the top and bottom ends. The top end is formed as a neck. The bottom end is formed as a recess. The neck and recess are essentially cylindrical. The neck and recess have a common axis and an essentially common length and diameter. The recess is adapted to receive a neck of another similarly configured bottle/container system. The neck is adapted to be coupled to a recess of another similarly configured bottle/container system.

Abstract: Numero Cubes and the Whole Number System are disclosed. In one embodiment, the system may comprise cubes, pegs, magnets, dividers, shafts, and a number placement panel. The shafts may comprise individual marks representing the base ten number system. The system may provide a method of learning mathematics through a cognitively authentic learning experience in constructing and building numbers.

Abstract: A foldable truss member suitable for commercial displays includes a plurality of side members that are adjacently hinged together. The side members include support members and bridging members having extensions. The side members are joined into a foldable structure with a hinge member between the support member and extensions of adjacent side members. A display structure can be formed by connecting locking members between two truss members.

Abstract: A combination toy building block and container for holding liquids and the like, wherein the functional configuration of the device permits both the carrying of a dispensable substance and the stacking of multiple containers, thereby enabling the imaginative play construction of buildings and objects such as, but not limited to, play forts, play houses, play cars and boats, statues, tables and chairs.

Abstract: Jelly blocks and jelly letters are disclosed. The jelly blocks and jelly letters may be made from an elastomer gel resulting in a soft, stretchable children's toy that has shape memory. The jelly blocks and jelly letters may be made from an elastomer gel that is formulated for tackiness to permit stacking of the blocks or sticking of the letters to a desired surface. The blocks and letters may be soft enough that a child could be struck with them without suffering injury.

Abstract: Disclosed is a temperature control method for a refrigerator which can minimize a deviation in refrigerant compartment temperature while minimizing the power consumption of the refrigerator.

Abstract: The object of this invention is to provide a block set for educational purposes. The block set features that a plurality of block units of the same color are integrated so as to build a block bar, and two or more block bars respectively of different colors are crosswisely combined to build a block bar combination, and two or more block bar combinations interconnect one another to thereby build a variety of structures having two or more colors, wherein the block bars of the same color are symmetrically disposed. The block set thus allows a user to learn a structural stability of the structures, a sense of balance, symmetry, a sense of harmony, etc. in a natural manner, through processes of building the variety of structures and repetition of those processes.

Abstract: A gaming system comprises a base for receiving a miniature figurine having distinct characteristics. The base may include at least one attachment member for interconnecting the base with an adjacent base. The gaming system may include a tracking member on each base for recording changing characteristics of the associated figurine. The gaming system includes a movable counter that may be integral with the game pieces and allows for easy measurement of various ranges. Structural units and structural unit guides allow for building a variety of structures used in the game.

Abstract: A foldable truss member suitable for commercial displays includes a plurality of side members that are adjacently hinged together. The side members include support members and bridging members having extensions. The side members are joined into a foldable structure with a hinge member between the support member and extensions of adjacent side members. The truss includes a locking frame that is removably attached to ends of the side members. A display structure can be formed by connecting a locking frame between two truss members.

Abstract: Gaming equipment for a variety of games has buildable structures formed of building blocks, movement measurement devices for measuring game piece movement and projectile range values, structural unit guides to aid in construction of the buildable structures, movable game pieces and universal sub-bases for toy miniatures.

Abstract: A building element for a set of toy building elements that are capable of being interconnected in a releasable engagement includes side walls having grooves and tongues, a top having a broad surface that extends toward the side walls and a primarily cylindrical projection extending above the broad surface; a open bottom; and an interior having a plurality of ribs with contact surfaces that are accessible through the open bottom and disposed for interconnecting with the projection on the top of another such building element. At least some of the contact surfaces of the interior ribs include lateral indentations; and the projection includes a circular lateral ridge disposed above the broad surface for being interconnected in a releasable restaining engagement within the indentations in the interior contact surfaces of the ribs of another such building element.

Abstract: A block set including a first block having a first and second cubic recess, the first and second cubic recess being diagonally opposed and the convergence points of the first and second cubic recesses being located along a common axis which is arranged a 45° angle relative to each of three orthogonal surfaces that define the first cubic recess and each of three orthogonal surfaces that define the second cubic recess. The block set also including a second cubic block adapted to be at least partially receivable within the first and second recesses of the first block.

Abstract: A system of elements of plastic material intended for the composition, by frictional insertion, of static or dynamic constructions having a game of didactic purpose, which comprises two kinds of main system elements, from which the first kind of elements has the character of a substantially tubular spacer whose end portions form female coupling members having a symmetry of order eight, while the second kind of elements has the character of a connector formed by a thin flange provided on both sides with male coupling members complementary to the female coupling members of the elements of the first kind but having a symmetry of order four.

Abstract: An educational and recreational toy system for toddlers including a plurality of toy components having various shapes and sizes. The various shapes and sizes of the components are based upon a unit measurement. Toy structures are provided, including a balance, a stringer, and a pegboard for integrated use with the components. The toy components may be used interchangeably/among the various toy structures. According to the invention, the system allows a child to improve motor, coordination, and thinking skills. This is accomplished by using the toy components—in conjunction with the toy structures—for matching, piling, patterning, and balancing exercises.

Abstract: An educational and entertainment device includes n layers stackable in a predetermined order one on top of the other to define a tower having n layers. The xth layer, where x varies between 1 and n, is divided into x sections, at least one of the x sections of the xth layer having a passage segment formed therethrough such that with the n layers stacked one on top of the other in the predetermined order, the passage segments of the n layers are in communication with each other to define a passage which extends through the tower. The device also includes an indicator element passable through the passage to confirm that the n layers have been assembled in the predetermined order.

Abstract: A color coded set of building blocks including a plurality of nesting blocks with diamond cross sections and at least one octahedron cap block. The blocks in each set are progressively sized so that when the individual blocks are stacked, they nest within each other to form a four-sided pyramid. The largest of the diamond cross section blocks acts as the base of the pyramid while the top of the pyramid is capped with an octahedron cap block. The blocks are stored in a clear pedestal base. The pedestal is also utilized as a design platform from which to build complex geometric designs. Each pedestal has four flared legs that provide stability to the platform while designs are constructed vertically and horizontally within it. By using linking elements, the designs can also be used to join together a plurality of the pedestal bases.

Abstract: An assembled building block formed by nineteen unit assemblies and a plurality of round holes for forming various geometrical shapes with corners of angles 60 degrees, 90 degrees and 120 degrees. The unit assemblies are formed by 1 and 3 to 6 small units integrally, there are five combination and nineteen sub-combination in the assembling of each unit assembly. The small unit of the unit assemblies is a polygon, and 9˜83 grooves for receiving the small units are formed on the surface of the building block seat. By the unit assemblies 1˜19 to conform to different building block seats, many different assemblies are formed. Moreover, different shapes, such a plane single layers, or a stacked double layers, or a stacked three layers, or pyramids with three to five layers can be formed with the present invention.

Abstract: An educational and recreational toy system for toddlers including a plurality of toy components having various shapes and sizes. The various shapes and sizes of the components are based upon a unit measurement. Toy structures are provided, including a balance, a stringer, and a pegboard for integrated use with the components. The toy components may be used interchangeably among the various toy structures. According to the invention, the system allows a child to improve motor, coordination, and thinking skills. This is accomplished by using the toy components—in conjunction with the toy structures—for matching, piling, patterning, and balancing exercises.

Abstract: The present invention concerns a building block toy, characterized in that a single kind of building block is used and in that the building block is of a unique shape. Specifically, the center of a flat equilateral triangular piece and the center of a flat hexagonal piece with the same thickness can be overlapped, and the three conjugated sides of the hexagonal piece can be connected to the three sides of the equilateral triangular piece upon stacking these two pieces in a parallel manner. The length of each side of the equilateral hexagonal piece is ⅓ of that of the side of the equilateral triangular piece. Thus, the parts where the equilateral triangular piece and the equilateral hexagonal piece overlap form three small equilateral triangular pieces (1, 2 and 3) of equal size.

Abstract: A pair of stackable, nestable blocks for elevating the leg of a bed to a plurality of selectable heights employs first and second blocks that each have upper and lower ends, with recesses being provided in at least one of the ends of each block that can be oriented upwardly to receive and support the foot or lower end region of a bed leg. Each block has a different length, which enables each block, used separately, to support the bed leg at a different height. Recesses of differing depths preferably are provided in opposite ends of at least one of the blocks, whereby the block or blocks that have dual-depth recesses can be inverted to provide bed leg support at two different heights. One of the two blocks preferably has a larger size than the other and is provided with recess(es) large enough to receive and support one or both of the end regions of the other of the blocks, whereby the smaller-size block can be stacked and nested atop the larger-size block to provide still more bed leg elevation heights.

Abstract: A set of novel architectural design blocks is disclosed. The design blocks may be used for education, instruction, and design purposes. Generally, the blocks contain a post member positioned in a generally upright position. Also, a beam member cooperating with the post member is provided and the beam member is positioned in a generally lateral position relative to the post member. Additionally, a rafter member cooperating with the post member and the beam member is included, with the rafter positioned in a sloping position relative to the post member. The post member comprises a 3 unit by 3 unit lateral surface area such that 9 unit members are formed therein with said center unit member being void so that 8 unit members are formed by said post member. The rafter will have in the preferred embodiment an 12 unit run by 8 unit rise.

Abstract: A three-dimension skill-development toy for small children is provided with a molded core element and a series of planar elements that may be stacked on the molded core element only by pattern matching and in one particular sequence to form a resulting fanciful and pleasing unitary shape.

Abstract: A toy building set has building elements which can be interconnected in a releasable frictional engagement. The building set comprises building elements having a first type of coupling means arranged in a two-dimensional modular pattern, and building elements having a coupling means of a second type dimensioned to touch coupling means of the first type. The building set moreover comprises building elements having a third type of coupling means, which are arranged in the two-dimensional modular pattern, but offset with respect to coupling means of the first type and dimensioned not to touch coupling means of that type, as well as building elements having at least one coupling means of a fourth type dimensioned to touch coupling means of the third type. Further, building elements for the building set are described.

Abstract: A sculpture amusement device includes a plurality of elements which are adapted be arranged into a plurality of two- and three-dimensional sculptures. The device includes a first stack of interior elements and a second stack of exterior elements. Each interior element includes a front surface and a rear surface, wherein a width of the interior element front surface incrementally decreases with increasing height position in its stack. Each exterior element includes first and second front surfaces, an inside surface disposed between the first and second front surfaces, and a rear surface. Each exterior element inside surface is complementary to each interior element rear surface at corresponding height positions within their respective stacks to form nested pairs of interior and exterior elements. That nesting feature allows efficient stacking and packaging of the set of elements, and allows a user to create attractive two- and three-dimensional sculptures from the elements.

Abstract: A set of blocks cut from the limbs and trunks of small trees is shown for making natural appearing stacks (20, 60). Each block has parallel upper and lower cuts (82, 84, 170, 171) across the blocks spaced a predetermined increment "I" or a multiple of increment "I" from each other. The remaining outer surfaces (90, 92) remain in their natural states complete with bark, protrusions, and other anomalies.

Abstract: An assembly toy is provided for constructing a three-dimensional composite object as defined by the successive edges of a plurality planar members stacked upon one another in a particular order. An axial structure such as a pair of rods is mounted to a base structure and passes through holes of each of the stacked members to align the holes of each such member and thereby fix its position and orientation. The toy may be provided as a puzzle with the user left to discover the particular order of stacking which results in the predetermined composite object, or each member may be labeled to indicate its stacking order.

Abstract: A multifunctional toy container including a hollow container body shaped like a motor vehicle and supported on wheels for keeping toy blocks, a handle fastened to the rear side of the container body for moving the container body on the ground by hand, and a top cover detachably covered on the container body and having a plurality of studs raised from the top side for mounting toy blocks to build up any of a variety of objects.

Abstract: A toy kit for forming a structure. Individual pieces include at least a cylinder, cone, cube and prism, and at least one additional piece. The piece can be assembled to form a structure, e.g. a sand castle. The pieces are hollow and open bottomed and include fixtures enabling mutual assembly together. Holes in their top walls permit passage of water or sand.

Abstract: A baby bottle formed of separable segments each adapted to educate and entertain a child during feeding comprising a plurality of hollow, generally cube-shaped blocks matable together to form a baby bottle, each of the blocks having four generally; the blocks including an uppermost block having at its upper extent screw threads, with a nipple and nipple support cap with internal threads removably mounted to the threads of the uppermost block; the blocks also including a lowermost block being formed with a lower end cap secured at its edges to the lowermost edges of the side walls thereof; the blocks also including at least one intermediate block, with each intermediate block being formed with an axial flange and external O-ring at its upper end and an internal circular flange adapted to be received over the flange and O-ring of an adjacent block; and an alpha-numeric character formed on at least one side wall of each block and an associated illustration of an object.

Abstract: A block toy has a plurality of regular hexahedral blocks each having a relief side having a relief surface, a printed side having a printed surface, and an apertured side having an aperture defined therein. A plurality of smaller blocks, which have sizes smaller than the regular hexahedral blocks, are each positionable on the apertured side of one of the regular hexahedral blocks when the smaller blocks are oriented in one direction. The smaller blocks can be fitted in the apertured side of one of the regular hexahedral blocks when the smaller blocks are oriented in an opposite direction.

Abstract: Base-ten blocks for teaching arithmetic to children, in which each block (19) has a projecting boss (27) with curved (bowed-out) sides (29) and an aperture (33) with straight sides (35), so that blocks (19) can be securely joined together to form multiples of units. Integrally made rows (37) of ten blocks each have two end bosses (41) for joining to other rows (37) to make flats (47) of one hundred units. Each flat has four bosses (51) for joining to other flats (47) to make a cube of one thousand units. The blocks have one color for units, a different color for rows of tens, a different color for flats of one hundred, and a still different color for cubes of one thousand. The blocks can be used to teach addition, multiplication, subtraction, division, etc., to children.

Abstract: Base-ten blocks for teaching arithmetic to children, in which each block (19) has a projecting boss (27) with curved (bowed-out) sides (29) and an aperture (33) with straight sides (35), so that blocks (19) can be securely joined together to form multiples of units. A row of integral blocks (37) has common wall thicknesses (42) between adjacent blocks equal to twice the thickness of the end wall (45) of the row so that the row can be correctly mated with a row of single blocks or end-to-end rows of shorter blocks. Integral rows (37) of ten blocks each have two end bosses (41) for joining to other rows (37) to make flats (47) of one hundred units. Each flat has four bosses (51) for joining to other flats (47) to make a cube of one thousand units. The blocks have one color for units, a different color for rows of tens, a different color for flats of one hundred, and a still different color for cubes of one thousand. The blocks can be used to teach addition, multiplication, subtraction, division, etc.

Abstract: A system of form bodies for use as a toy building blocks, decorative objects, in particular for display use, furniture structures, sculptural building components etc., wherein each form body has the shape of a polyhedron, in which polygonal side faces with each other form polyhedral outward extending protuberances and/or polyhedral inward extending notches for the assembling of differently shaped bodies into spatial structures. In a first group of form bodies each form body is shaped on the basis of a cube and the protuberances and/or notches of the form body are shaped on the basis of a subbody of a cuve and with a shape like a pyramid with a square base, two of the side faces being perpendicular to the base at adajcent sides thereof and each of them has the form of an isosceles right triangle.

Abstract: A stacking puzzle including a plurality of stackable, game pieces and one or more solid game rods. Each of the game pieces includes an aperture extending obliquely therethrough. When the game pieces are properly stacked and oriented relative to one another, the oblique apertures line up and allow the game rods to be inserted through all the game pieces. However, the game pieces must be stacked in the proper order and must be placed in the proper orientation relative to one another in order for the apertures to align properly. Although there are a multitude of incorrect ways to arrange the game pieces, only one correct arrangement causes the apertures to align and thereby permit the game rod to be inserted through the game pieces. In one embodiment, the faces of the game pieces are made nonparallel to provide an additional degree of freedom and thereby further increase the challenge of the puzzle.

Abstract: A construction toy configured as a humanoid figurine formed from: a torso having a front wall and a rear wall, a head area, downwardly extending legs and outwardly extending arms. The torso and its front and rear walls provide first and second attachment surfaces which are complementally formed mirror images, one of the other so as to provide connecting elements when the figurines are to be stacked and interconnected. Because the nature of the attachment surfaces is neutral with respect to its center, the connecting elements can also allow attachment to an adjacent stack of figurines in a rotational pattern. The connecting elements also allows quadrans of the torso to be stacked forming imbrications. The head has a profile provided with a first fastening elements for interconnection with either the second attachment surface or other fastening elements. Each leg is formed from two pieces of planar stock spaced one from the other defining a groove. The groove defines a second fastening elements.

Abstract: A construction toy formed from a plurality of building blocks. Each building block is formed with a multiplicity of facets defining the exterior and each facet is provided with structure for attachment to another facet. Some facets are embodied as including a plurality of radially extending vanes, others are complementally formed recesses. Preferably these recesses and vanes are disposed on top and bottom walls of a building block, defining two of the facets. A periphery circumscribes the top and bottom walls and defines a plurality of additional facets. This periphery is provided with further structure for interconnection with other facets on the block. Some peripheries are provided with projections, others with channels. The projections can be received not only in the channels, but also within recesses on the bottom walls. The channels not only can receive projections, but also can receive the vanes on the top wall of the block.

Abstract: A toy vehicle constructed as a shape identification toy, wherein the toy vehicle comprises a plurality of components which interconnect due to a shaped member being provided on one of the plurality of components co-operating with a corresponding shaped member provided on another of the plurality of components.

Abstract: A method of playing a board game, where the game comprises a play surface and multi-segmented playing pieces representing characters adapted to stand upright on the surface. Each character is comprised of a stack of segments. By progressively removing segments from the bottom of the stack upwardly, the character appears to be sinding deeper and deeper below the surface, as for example, quicksand or a body of water. As segments are added back to the bottom of the stack in the reverse order, the character appears to emerge upwardly again. Portions of adjacent segments interconnect to maintain the segments in the desired stacked condition and relative orientation to one another.

Abstract: Polygonal construction modules are capable of being connected together by their edges and by their faces to create many different three-dimensional shapes. Each module has a generally planar body with edge faces, a top face and a bottom. Each edge face has a plurality of outwardly projecting fingers designed to provide a snap-together lateral interlock between fingers of adjacent modules while permitting hinging or rotation between modules on an axis parallel to the side face. Projecting upwardly from each top face is at least one annular connector element for establishing a friction fit with a like connector element in face-to-face interlocking engagement. The connector element includes a series of projections arranged in a uniform circular array, each projection being segmental in shape with radial side walls.