Abstract: The air damper includes a housing with cylindrical walls and a piston assembly reciprocating therein. The piston assembly includes an interior surface against which a seal abuts. The interior surface is textured in a grained pattern so that interstices are formed between the seal and the interior surface thereby forming an effective air passageway for damping. A cylindrical spacer spaces the interior surface from a retainer and the seal is engaged around the cylindrical spacer and between the retainer and the interior surface. An alternative embodiment inserts textile material through a damping orifice in order to vary the rate of damping.

Abstract: An improved one piece drive fastener having a head and a shank, the shank including a generally non-circular cross-section presenting a plurality of generally flat, axially extending surfaces. Each of the flat surfaces on the shank carry a plurality of axially spaced flexible resilient wing elements; the wings being flexed along the straight line connection with the flat surfaces. Certain wings extending from and positioned in spaced relation along at least one said surfaces being angularly disposed so as to tilt in the direction of said head and further including means formed integrally with each of said certain wings to substantially increase the force required for removal of said fastener from a cooperating aperture as compared to the force required to introduce said fastener into said aperture. Said fastener with its flat surfaces permitting the manufacture of said fastener in a simple two-plate mold design.

Abstract: A multi-part fastener assembly for attachment of a carpet-like member to a support. The fastener is designed to minimize snagging and/or scraping-type of engagement with objects that come in contact therewith. The exposed fastener part is an annular member which has a radiussed outer edge from which a plurality of rigid projections extend. The projections are designed to be able to penetrate the carpet-like member and a radially extending flange of another fastener part and be folded to fixedly position the fastener relative to the carpet-like member. The radially extending flange has areas of reduced thickness to ease the projections therethrough and is deflected to create an annular mounding of the carpet-like member around the annular member to cooperate therewith in increasing the resistance of the fastener to snagging type of engagement.