The Waterline PEX barb polybutylene adapter is made of a lead-free DZR brass, and is an easy to install, low-cost solution to connect PEX tubing to polybutylene pipe. Waterline PEX barb fittings are compatible for potable water distribution and hydronic heating applications. This product includes 2 color coordinated crimp rings – the included black crimp ring is intended for PEX while the copper-colored crimp ring is for use on polybutylene pipe.