A drive cavity for a threaded fastener which is compatible with a variety of wrench drivers having hexagon-based profiles. The drive cavity is a prismatic projection of a multi-, primarily flat-sided, profile having its radially inner margins defined by the mid-sides of a common base hexagon and its...http://www.google.fr/patents/US4459074?utm_source=gb-gplus-shareBrevet US4459074 - Socket drive
