Watts Poly Alloy CrimpRing fittings are a perfect match for Watts PEX tubing and potable use. These fittings are produced from an engineered thermoplastic polymer called ACUDEL. ACUDEL resin offers many improved performance characteristics that make it an excellent choice for molded components installed in the demanding environment of a hot and cold-water plumbing system. Poly Alloy fittings are made to ASTM F2159 and F877 standards. They have the NSF-pw rating and are certified to Canadian Standard Association B137.5.