Hayward TC10050STE 1/2-Inch PVC TC Series True Union Check Valve with EPDM Seals and Socket/Threaded End Connection TC Series true union check valves with EPDM seals and O-rings Made of heavy wall plastic material True union check valves prevent backflow; meets ASTM and NSF standards True union design allows easy removal from system without breaking down piping connections Pipe measures 1/2-inch socket/threaded end connection