US Patent 7228764 Maximum engagement wrench

A tool device is described which comprises an orifice which has at least one engagement end formed to control the rotation of a work piece. The tool device has a peripheral terminal end at the engagement end. The orifice is defined by an inner wall of alternating recessed regions and engagement regions arranged about an imaginary central axis. The recessed regions and engagement regions extend longitudinally and substantially parallel to the imaginary central axis. And, at least a part of each engagement region extends farther towards the peripheral terminal end of the tool device than at least a part of each recessed region.