Fastener

Claim 1

A fastener comprising a counterpart element and a main element which is insertable into said counterpart element, said main element having a cylindrical insert portion including an extruded skirt element having a raidally extending first portion of semi-circular cross-section and a second leading end portion with walls tapered towards the axis of the cylindrical insert portion and a plurality of slots in the open end thereof, said counterpart element including a cylindrical head portion in the center thereof and a flange portion around said cylindrical head, the cylindrical head comprising in sequence a first aperture means having a diameter smaller than the diameter of said first portion of said skirt element and a ring shaped groove for Loosely engaging said first portion of said skirt element therein, shoulder means having a diameter less than the diameter of said first aperture means, and a second aperture means having a diameter greater than the diameter of said skirt element wherein when said main element is partially inserted into said counterpart element, said first aperture means engages said skirt element to temporarily hold said main element in said counterpart element and when said main element is completely inserted into said counterpart element said skirt element is firmly held in said second aperture means by said shoulder means.