Genuine OEM Audi Engine Coolant Hose, part number 4K2121081H. This flexible hose is a vital component of the engine cooling system, responsible for carrying coolant to or from the expansion tank. It ensures proper circulation and pressure regulation within the system. Weighing 0.028 kg and measuring 0.285 m in length, this hose is designed for specific routing and temperature resistance. Using a genuine OEM coolant hose guarantees the correct material composition, diameter, and flexibility to withstand engine heat and pressure, preventing leaks and maintaining cooling efficiency.