OBD1761 Features: * Hardened for extra strength * Prevents rounding of fasteners" corners * Thin wall design fits into tight spots * Chamfered opening slips easily over fasteners and holds securely * ""Lobular"" design exerts force on flats of fasteners * Drive Size: 1/2 in * Drive Type: Square * Testing and approvals: * Meets ANSI Spec. B107.1 * Meets Federal Standards GGG-W-641e