BRAND NEW !!! The check valve is an important part of any air compressor. The air compressor check valve can be found on almost any compressor out there. The check valve has only one function: to let air flow from one side to the other, while blocking air flow in the opposite direction. Once the compressed air passes the check valve, there is no way it can go back again. MADE IN USA 450 PSI MAX PRESSURE 400 DEG F. MAX TEMPERATURE 1/2" FEMALE (NPT) PIPE THREAD TOP X 1/2" MALE (NPT) PIPE THREAD OUTLET TO TANK 1/8" UNLOADER PORT INCLUDED 20 SCFM FLOW RATE Large Quantity inquiries are welcome!! We provide discount on high volume orders!