3/8" Drive x 3/8" universal joint Made with a friction ball retainerTested to the highest specifications to deliver outstanding performance at the most competitive costMade of high quality steel (chrome-molybdenum)Lifetime WarrantyThis 3/8" drive universal joint has a friction ball retainer, which is a socket retention device. A spring loaded ball that line up with the socket retainer hole. Use caution when using this system because the socket is held in place only by spring pressure on the steel ball.