The SharkBite PEX Poly Alloy Barb End Cap is an easy to install and low cost solution to cap off a PEX tubing line. The SharkBite PEX Poly Alloy Barb fittings are compatible for potable water distribution and hydronic heating applications. These fittings can be used in both a stainless steel clamp system, or a copper crimp ring system as well (each sold separately). Approvals: ASTM 2159, NSF/ANSI 61, NSF 372.