Stanley Proto J77270P Proto 3/8-Inch Drive Impact Universal Joint Tight tolerances for snug fit on fastener Used wherever powered drive tools are used to install or remove fasteners Designed to withstand the high torque and force associated with impact tools in repetitive application Features two through holes and a groove to accept a Proto Retaining Ring or pin and O-ring to help secure the socket to the drive tool anvil Position at appropriate angle to turn fasteners where obstructions prevent a straight application