Made from superior S2 steel to meet or exceed torque specifications. All bit sockets are a 2 piece design, 20 percent stronger than one piece style for longer life. Backed by OTC's Lifetime Marathon warranty Set includes: 1/4" drive sizes T10, T15, T20, T25, T27 and T30; 3/8" sizes T40, T45, T47, T50 and T55; and 1/2" drive size T60.