Genuine OEM Audi Fuel Tank Breather Line, part number 4K0201991AG. This component is essential for the fuel system's evaporative emissions control, allowing air to enter and exit the fuel tank to equalize pressure and manage fuel vapor. It connects the fuel tank to the activated charcoal canister. Weighing 0.12 kg, this line measures 1.35 m in length. Using a genuine OEM breather line ensures proper material compatibility with fuel vapors, correct routing, and reliable function for emissions compliance.