Genuine OEM Audi Alternator Poly-V-Belt, part number 05A903137A. This multi-ribbed serpentine belt is responsible for transmitting power from the engine's crankshaft to various accessory components, including the alternator, power steering pump, and air conditioning compressor. Its robust construction ensures efficient power transfer and resistance to wear and stretching. Choosing a genuine OEM poly-V-belt guarantees the correct length, tension, and material composition for optimal accessory drive performance and long service life, preventing squealing or premature failure.