PROTO® Black oxide finish metric deep impact socket are ideal for use on stubborn or damaged fasteners and also on fasteners made from soft materials. The TORQUEPLUS™ design is a high performance drive configuration which allows for quick and easy socket engagement to the fastener flats, not the corners. The TORQUEPLUS™ configuration employs a radius-corner design, shifting contact area and stress away from the fastener corners and distributing contact stresses over a large area of the socket, minimizing slippage. The TORQUEPLUS™ internal design minimizes fastener rounding, helps to extend fastener life and allows the user to more easily turn worn, rounded or rusted fasteners. Stamped size for easy reference. Side locking hole. ASME B107.110-2012.