Patent ID: 7293949

Claim:
A fastener system comprising: a fastener constructed with a head and a shank, said shank having a longitudinal axis, and said head constructed having a recess formed at its end, wherein said recess comprises; a central portion and a plurality of wings radiating outwardly from the central portion, each of the wings having an installation wall and a removal wall, the wings being configured so that at least one of the installation or removal walls defines a segment of a spiral over its extent; a non-driving transition surface extending between each of the installation and removal walls of adjacent wings, at the radially inner most extent of said wings, each of said transition surfaces formed having an interference contour extending radially inward into the central portion, said contour being tapered from a first radial distance from the longitudinal axis at a top portion thereof to a second radial distance from said longitudinal axis at a bottom portion thereof; and wherein said first radial distance is larger than said second radial distance and wherein said interference contours of said transition surfaces are diametrically opposed across said recess.