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. 450 PSI MAX PRESSURE 400 DEG F. MAX TEMPERATUREMADE IN USA 1/2" COMPRESSION TOP INLET X 1/2" MALE (NPT) PIPE THEAD OUTLET TO TANK 1/8" UNLOADER PORT INCLUDED20 SCFM FLOW RATE 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. 450 PSI MAX PRESSURE 400 DEG F. MAX TEMPERATURE MADE IN USA 1/8" UNLOADER PORT INCLUDED 20 SCFM FLOW RATE