Genuine OEM Volkswagen Water Coolant Hose, part number 6Y0121049H. This essential hose is responsible for transporting hot coolant between engine components and the radiator, playing a vital role in maintaining optimal engine operating temperature. The diagram shows it as part 15, connecting to the radiator. Weighing 0.336 kg with dimensions of 0.36m x 0.18m x 0.06m, it is designed for specific routing and pressure. Using a genuine OEM coolant hose ensures correct material composition for heat and chemical resistance, precise routing geometry, and reliable sealing, preventing leaks and maintaining cooling system efficiency.