Genuine OEM Audi coolant hose, part number 420121036A. This hose is designed to transport engine coolant throughout the cooling system, maintaining optimal operating temperatures. It is manufactured from high-grade, heat-resistant rubber to prevent leaks and withstand the pressure cycles of the cooling circuit. Genuine OEM hoses are critical for maintaining the correct routing geometry, preventing kinks or collapses that could restrict flow and lead to engine overheating.