Cash Acme 2008-0000 Shark Bite SharkBite Check Valve, 1/2-by-1/2-Inch General all purpose spring loaded check valve , this item cannot ship to CA or VT Prevents the reverse flow of water through the water supply line Installed in seconds on copper, CTS, CPVC and PEX Can be installed horizontally or vertically 1/2-Inch by 1/2-Inch