PEX-A pipe is cross-linked, high-density polyethylene. All Apollo Expansion PEX is available in red, white and blue for easy identification of hot, cold, and main water lines. Apollo uses the high-pressure peroxide method of cross-linking which is also known as PEX-A. Apollo Expansion PEX pipe is produced using the high-pressure peroxide method for crosslinked polyethylene (PEXa) in accordance with ASTM F876, F877, CSA B137.5 and PPI TR-3, and is certified to NSF 14/61 standards. Apollo Expansion PEX pipe also meets the requirements of ASTM F2023 for chlorine resistance. Apollo Expansion PEX pipe is manufactured using a quality management system which has been certified to the latest version of ISO 9001.