Apollo Expansion PEX Couplings are manufactured using lead free dezincification resistant brass. Exclusively designed for use with PEX-a pipe, the fittings offer a larger I.D. than traditional crimp fittings for full flow resulting in fast delivery of potable water. For use with PEX-a pipe only. Suitable for use in hot and cold domestic potable water and hydronic heating and cooling piping systems. Compatible with Uponor (Wirsbo) ProPEX™ piping systems. *ProPEX® is a trademark of Uponor.