Copper Press x PEX Expansion style adapters are used to transition from a copper pipe to PEX-A pipe using press and PEX expansion methods. Press side is the same style as most press fittings on the market, including brands such as Viega, Apollo, Nibco and others. PEX-A side is F1960 expansion style and is compatible with PEX-A pipe only (Everhot, Uponor/Wirsbo, Sioux Chief, Rehau, Mr PEX, etc.)