Genuine OEM Audi Coolant Hose, part number 427121036A. This hose is responsible for transporting coolant between various engine components and the radiator, playing a critical role in engine temperature regulation. It is part of the engine cooling system. Constructed from reinforced, heat-resistant rubber, it is designed to withstand high temperatures and pressures. Genuine OEM hoses ensure the correct diameter, routing, and material composition for reliable coolant flow and system integrity.