Genuine OEM Audi Radiator Lower Coolant Hose, part number 3C0122051BK. This essential hose is responsible for transporting cooled fluid from the radiator back to the engine, playing a critical role in maintaining optimal engine operating temperature. Weighing 0.38 kg and measuring 0.4 meters in length, a genuine OEM coolant hose ensures the correct routing geometry, material composition, and resistance to high temperatures and pressures for reliable cooling system performance.