The OEMTOOLS 13-pc Star Bit Socket Set, No. 22977, comes in many sizes, including (1/4” drive) T8, T10, T15, T20, T25, T27, T30, (3/8” drive) T40, T45, T47, T50, T55, and (1/2” drive) T60. The long-lasting bits are made of heat-treated S2 steel while the reinforced chrome vanadium steel sockets are designed to give extra turning power. The bits are made with fully refined hard chrome plated finish and zinc phosphate to prevent rust and corrosion The precision-made set exceeds ANSI standards and comes in a sturdy blow molded case for convenient and organized storage.