The M18 ProPEX expansion heads are precision engineered for accurate expansion of UpoNr PEX-a tubing for ProPEX fittings. Featuring the auto-rotation interface for Milwaukee cordless ProPEX expansion tools, the heads are Nt only compatible with M18 tools, but also fit most UpoNr cordless tools. Made from high strength steel, the chrome plated segments and black oxide ring combine durability with weather resistance. Color coded rings for easy size recognition add convenience.