Patent ID: 8650723

Claim:
A mechanical snap fastener for holding two pieces of material together, comprising: a male component comprising a base, a pin having an enlarged tip and a first anti-rotation surface displaced peripherally from the pin; a female component comprising a retaining element for releasably holding the enlarged tip of the pin, a socket body having a central hole which receives the pin and into which the retaining element protrudes and a second anti-rotation surface displaced peripherally from the central hole, wherein the male component is attachable to a first piece of material, the female component is attachable to a second piece of material, the first anti-rotation surface of the male component and the second anti-rotation surface of the female component interact to prevent rotation of the male component relative to the female component when the components are fastened together, and at least one of the anti-rotation surfaces has a symmetrical curved outer edge configured to bear against an opposing male or female component to bring the male and female components into alignment when they are not aligned in an indexed fastening position, the at least one anti-rotation surface having a dimension measured between a base of the at least one anti-rotation surface and the curved outer edge which increases with distance away from ends of the curved outer edge.