ProtoGrip™ Magnetic Sockets use high-strength magnets made from a rare earth magnet alloy/nylon blend. ProtoGrip™ Magnetic Sockets require no bushings to hold the magnet in place. Allows room for more magnet material, helping increase total magnetic strength. Designed to easily pick up heavy fasteners and hold them tightly during use. Socket size stamped on tool for easy identification. Side locking hole.