The Mibro 312411 4 Piece Magnetic Nut Setter Set helps maintain a secure hold to keep fasteners firmly in place. The magnetic nut setter set is made from cold-forged and hardened chrome vanadium steel for durability and long-lasting use. This nut setter set also includes 1/4 in. 5/16 in., 3/8 in., and 7/16 in.