1/2" Radiator Square Head Stepped Wrench can be used with 1/2" ratchet and other drives. 1/2" spud wrench is designed to repair most household radiator valves, plugs, caps, reservoir connectors, etc. Used for disassembly and assembly of most household radiator valves. For example: loosen or tighten the nut on the toilet, install the water heater, remove the nozzle on the floor radiator, turn the slip nut in the sink slot. The stepped radiator wrench has in 5 different sizes including 10mm, 11mm, 12.5mm, 16mm and 21mm. Staggered Chrome Vanadium Steel Radiator Wrench for added strength and durability.