Hydrant wrench

They are usually adjustable so as to fit different sized hydrant nuts.

In France, The wrench is called "Guillemin wrench" (French: clef Guillemin, pronounced [kle ɡijəmɛ̃]), but the firefighters call it "tricoise wrench" (clef tricoise, [kle tʁikwaz]).

Big tricoise wrenches are placed in fire trucks, and are mainly used to fasten the big hoses, e.g. ∅110 mm hoses to feed the pumper tank from the hydrant (∅100 mm for the clutch).

Small tricoise are made of brass and hang at the fire belts; they are used to fasten the small hoses, e.g., ∅70mm to ∅22mm hoses (∅65mm to ∅20mm clutches).

The shape is sometimes adapted so it can be used as a tool for other purposes; it is then called "polycoise wrench" or "Deschamps wrench".