The STEELMAN PRO 79400 1/2-Inch Drive 19mm x 21mm 6-Point X-Thin Wall Metric Impact Flip Socket was designed to save you time by helping you maximizing efficiency. This dual-ended, 6-point metric impact grade flip socket allows you to work on both 19mm and 21mm lug nuts and fasteners without having to constantly switch sockets. Made of durable and hardened chromoly steel which is then given a black phosphate protective coating, this socket is designed to meet or exceed 150% proof of torque under ASME tool performance testing standards. Fitting easily over an impact extension or onto an impact wrench's extended anvil, this socket's recessed edges provide the most accurate fit possible, gripping fasteners by the sides and not the edges which results in reduced slippage and rounding/fastener damage. In addition, the extra-thin-walled design allows this socket to reach fasteners where the minimal side clearance makes them impossible to reach with standard, thicker walled sockets. Laser-etched size callouts make identification among other sockets easy and they will not rub off or wear away with use. Whether you’re a professional mechanic at a repair or tire shop, or just love to work on your own cars and vehicles, this flip impact socket is a must for working efficiently!