John Guest offers Speedfit Test Caps to provide a leak-proof seal in conjunction with its push-fit fittings for securing PEX, CPVC or copper piping in domestic hot and cold water systems, and in hydronic heating applications. Simply push the fitting fully on to the pipe. Should work need to stop or restart due to an interruption or a need to extend the piping system, push the collet towards the body of the fitting and pull the pipe to release. Speedfit Test Caps are lead- and corrosion-free, nontoxic and resist scale