Reaching over a radiator to open and close a petcock, especially a rusty one, can be a real belly-buster, as well as a knuckle-knocker. Simplify the task with this petcock socket. Two-slot design matches most types of petcocks for radiators, engine blocks, air compressors, storage tanks, etc. Requires a 1/4in. drive ratchet or 7/8in. wrench.