Stanley Proto J5221MH 3/8-Inch Drive Socket, 21mm, 6 Point Proto 6 Point Sockets are ideal for use on stubborn or damaged fasteners and also on fasteners made from soft materials The Torque Plus design is a high performance drive configuration which allows for quick and easy socket engagement to the fastener flats The Torque Plus configuration employs a radius-corner design, shifting contact area and stress away from the fastener corners The Torque Plus internal design minimizes fastener rounding, helps to extend fastener life