Patent ID: 7568872

Claim:
In a fastener having a drive socket for receiving a key driver having a plurality of flat surfaces and a plurality of corners at intersections between the plurality of flat surfaces, the improvement comprising: the drive socket having a surface defining a first plurality of lobes of substantially equal radius located substantially equidistant from a center of the fastener and substantially equidistant circumferentially from each other, the first plurality of lobes including a curved portion, a flat surface which is located adjacent and tangential to the curved portion, and a first apex between said curved portion and said flat surface portion, said flat surface portions of said first plurality of lobes receiving a first set of alternating ones of said plurality of flat surfaces of the key driver; the surface of the drive socket defining a second plurality of lobes having rounded surfaces of substantially equal radius not including a flat surface portion positioned about the center of the fastener, each of the rounded surfaces including a second apex, each of the second plurality of lobes being located substantially opposite one of the first plurality of lobes and substantially equidistant from the center of the fastener, and the second plurality of lobes receiving a second set of alternating ones of said plurality of flat surfaces of the key driver; and the surface of the drive socket defining curved recesses smoothly transitioning between the first plurality of lobes and the second plurality of lobes, each of said curved portions of said first plurality of lobes being directly connected to one of said curved recesses, and the plurality of corners of the key driver remaining out of contact with said curved recesses.