Genuine OEM Audi Coolant Hose, part number 4K2121123A. This hose is a vital component of the engine cooling system, responsible for circulating coolant between the expansion tank and other cooling system components. It ensures the engine maintains optimal operating temperature. The hose is precisely engineered for its specific routing within the engine bay. Made from high-quality, heat-resistant rubber, genuine OEM hoses guarantee correct fluid resistance and pressure handling for reliable, leak-free performance.