Check valve grommet. A Grommet for a Power Brake Booster Vacuum switch. A rubber ring with a hole in the center which provides protection through which the Brake Power Booster Unit Sensor or a part of said component passes through. Power Brake Booster Check Valve Seal. Power Brake Booster Grommet. Check Valve Seal. Sensor. Pressure switch. Included with: Booster, Booster Part cannot be reused/reinstalled, Booster assembly, Booster assembly Part cannot be reused/reinstalled, Check Valve, Power Booster.