Professional tool for commercial or occasional use. Designed for repairing most household radiator valves. Suitable for loosening or tightening spud nuts on toilets, installing water heaters, removing spuds on floor radiators, and turning slip nuts on P traps under sinks. Features a 1/2" drive compatible with any 1/2" drive ratchet or power bar extension. Insert into the radiator nipple until the proper size is reached. Pipe wrench can remove or tighten, preventing damage to the nipple. Includes five hexagonal sizes: 10mm, 11mm, 12.5mm, 16mm, and 21mm. Imperial equivalent sizes are 3/8", 7/16", and 1/2". Suitable for use on radiator valve trails, lugs, nipples, and tank connectors. Manufactured from chrome vanadium steel for strength and durability. Complete with pin groove.