Genuine OEM Audi Radiator Coolant Upper Hose, part number 4E0121101BR. This hose is crucial for the engine cooling system, carrying hot coolant from the engine to the radiator for heat dissipation. It is positioned as the upper connection in the cooling circuit. Constructed from durable rubber and plastic, it measures approximately 0.38 meters in length. Using a genuine OEM hose ensures correct routing geometry, proper sealing, and resistance to high temperatures and pressures, preventing leaks and maintaining cooling system integrity.