T-Rex VRC-050 50 mm 2 inch swing check valve in cast iron with roll groove portsT Rex VRC 050 50 mm 2 inch swing check valve with roll groove ports Cast iron material Swing check valves are among the most common types of check valves frequently used to manage a high horizontal flow the water pressure opens the disc to allow the water through ideal for use on hydrant fill pipework to keep the pipe primed keeps the water off your boots when you disconnect the hose