Genuine OEM Volkswagen Vent Tube, part number 4E0121102N. This tube is a critical component of the engine cooling system, designed to allow air to escape the cooling circuit to prevent airlocks and ensure efficient coolant circulation. It is positioned within the cooling assembly as illustrated in the technical diagram. Genuine OEM vent tubes are manufactured with the correct material composition and wall thickness to withstand high temperatures and pressure fluctuations, ensuring a reliable seal and preventing coolant leaks.