Impact universal joint adapters let you reach fasteners in tight corners and spaces with power tools Ball spring design distributes torque evenly and works in a smooth 360 degree rotation Spring-loaded detent ball securely holds sockets in place Premium Chrome Molybdenum steel tempered with our proprietary heat treatment process to withstand more torque from power tools 3-piece set: 1/4 in. drive, 3/8 in. drive, and 1/2 in. drive impact universal joints