Genuine OEM Audi Headlight Housing De-Airing Hose, part number 83A941717A. This hose is located on the left side of the vehicle and allows air to escape from the headlight housing, preventing condensation buildup and maintaining optical clarity. It is a small, bent component integral to the headlight assembly. Using a genuine OEM de-airing hose ensures proper ventilation and sealing, crucial for the longevity and performance of the headlight unit.