PROTO® Black oxide finish 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. ASME B107.110-2012.