Apollo ExpansionPEX 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.