Stanley® Proto® 6 Point 1/4" Drive ProtoGrip™ High Strength Magnetic Power Socket measuring 3/8" uses high strength magnets made from a rare earth magnet alloy/nylon blend. It does not require any bushings to hold the magnet in place. It is designed to easily pick up heavy fasteners and hold them tightly during use. It has strong magnetic hold that helps to increase the efficiency when installing fasteners. It is used in automated and hand impact socket applications.