Genuine OEM Mercedes-Benz Fuel Pump Check Valve, part number A0000900310. This valve is installed in the fuel system to prevent fuel from draining back into the tank when the engine is off. By maintaining residual fuel pressure, it ensures quicker engine starts and consistent fuel delivery. The valve is a small but critical component for the overall health and efficiency of the fuel system. Genuine OEM parts ensure precise sealing and reliable operation.