8020GST is a 2" true union ball check valve that comes with socket and threaded ends. This valve is manufactured with EPDM seats and can handle temperatures that range up to 140 degrees F. This ball check valve has a floating ball inside that checks into place once the flow of the system is turned off to prevent any backflow into the system. The union ends allow for easy repair or replacement of the valve. The valve must be orientated correctly inline with the flow arrows so that I works and checks properly. PVC Pipe Supplies stocks many of these valves and offers discounted online pricing to all of our valued customers.