Thin wall design that provides extra clearance in tight spaces. Made with a friction ball retainer. Tested to the highest specifications to deliver outstanding performance at the most competitive cost. Made of high quality steel (chrome-molybdenum) Lifetime Warranty. This 3/8" drive thin wall Universal joint impact socket with 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.