Genuine OEM Volkswagen Coolant Hose, part number 7C0819320. This hose connects components within the auxiliary heater coolant circuit to facilitate heat transfer. It is located at position 13 in the diagram. This part has a length of 0.155 meters. Genuine OEM coolant hoses are manufactured to precise specifications to ensure proper flow and resistance to heat and pressure, preventing leaks and maintaining auxiliary heating system efficiency.