Genuine OEM Audi Coolant Hose, part number 420121108A. This hose is a critical component of the engine's cooling system, responsible for transporting coolant between various parts of the engine and radiator. It is located within the engine cooling system assembly. Constructed from high-quality, heat-resistant rubber, this hose is designed for durability and reliable fluid transfer. Genuine OEM coolant hoses are essential for maintaining the correct flow and pressure within the cooling system, preventing leaks and ensuring optimal engine temperature.