This push-to-connect fitting is designed to make PEX-to-PEX connections in potable water and radiant heating (including underground or behind-the-wall) applications with no access panels required. No soldering, clamps, unions or glue required. Insert PEX pipe into the fitting deep enough to be sealed by o-ring. Once inserted, stainless steel teeth bite down and grip the pipe. Green indicator ring will display in the slots around the fitting to visually display that permanent inner-diameter connection is secure. Made of engineered polymer. Fittings are rated up to 80 psi @ 200 F, 100 psi @ 180 F, and 160 psi @ 73.4 F.