Genuine OEM Audi Coolant Hose with Regulator, part number 4F0121030D. This critical component carries coolant and helps regulate its flow within the engine cooling system, maintaining optimal operating temperatures. It is a precisely engineered hose, weighing approximately 0.715 kg with dimensions of 0.436m length, 0.3m width, and 0.106m height. Choosing a genuine OEM coolant hose ensures the correct routing geometry, material resistance to heat and pressure, and integrated regulator function for reliable engine cooling system performance.