A drive socket for a male threaded fastener includes a plurality of rounded lobes of equal radius which are located equidistant from the center of the fastener and an equal distance from each other. The drive socket also includes flat surfaces located opposite the lobes and equidistant from the center...http://www.google.fr/patents/US6736580?utm_source=gb-gplus-shareBrevet US6736580 - Lobed drive for hi-lite fastener
