Genuine OEM Audi Upper Radiator Hose, part number 4F0121101F. This critical component of the engine cooling system connects the engine to the upper inlet of the radiator, allowing hot coolant to flow for heat dissipation. Constructed from durable, heat-resistant rubber with a protective fabric sleeve, it is designed to withstand high temperatures and pressures. Using a genuine OEM upper radiator hose ensures precise fitment, correct routing, and material integrity, which are essential for preventing leaks, maintaining cooling efficiency, and protecting the engine from overheating.