Found under the following brands:
Annovi Reverberi-AR, Westward, Bostitch, Black & Decker, Craftsman, Devilbiss Air Power, DeWalt, Emglo, Excell, Porter Cable, Speedaire
This one way valve allows your motor to start easier. It also keep the air in the tank and prevents backfeeding to your pressure switch. If your pressure switch is leaking out of the small bleeder valve on the side or if located underneath, order this valve.