1/4" drive set includes a steel universal socket to fit radiators, engine blocks, storage tanks, etc. with an O-ring to hold a 7/8" wrench in place. Set also has a molded plastic socket to fit narrow wing plastic drain fittings, both plug and flow-through types. Socket comes with an O-ring to hold a 7/8" wrench in place Stop using pliers to open and close petcock drains. This socket is especially made for radiator and engine petcock drains and won't crush the drain tube.