Genuine OEM Audi Engine Breather Line, part number 4G0121081BN. This hose is located on the front right side of the engine, designed to allow engine gases to vent, which is crucial for maintaining proper crankcase pressure and preventing oil leaks. Its precise routing and material composition ensure resistance to oil and heat. Using a genuine OEM breather line guarantees correct fitment and material integrity, preventing vacuum leaks and ensuring optimal engine performance.