Fabricated Check Valve -AN20 Male Outlets. Providing the same function as the Universal Check Valves, our Fabricated Check Valves provide a less expensive, lighter weight alternative to the racer who wont be reconfiguring their plumbing. Fabricated Check Valves are most comonly found on Drag, Sprint, Midget and Outlaw cars. C&R check valves are also designed to work with the C&R Water Circulator and Drag Chillers as well as Portable Engine Heaters and Combo Heaters. Check valves are used to insure directional water flow through the entire cooling system. They are designed to fit the current radiator plumbing and are available in AN and push-on hose sizes. C&R suggests the Jiffy-Tite Quick Disconnect fittings.