Zurn PEX® XL-Low Lead Brass Barb x MPT Adapter. The QQMC_GX adapter is used to transition from female pipe thread to PEX tubing. Manufactured from EcoBrass®,C69300. These fittings, as a system with Zurn PEX® tube, are pressure rated at 160 PSI at 73 deg F, 100 PSI at 180 deg F, and 80 PSI at 200 deg F. These fittings are listed by NSF as complying with the following standards NSF/ANSI Standard 14, NSF/ANSI Standard 61 including Annex G, ASTM F877, CSA B137.5 and ASTM F1807.