Genuine OEM Audi Alternator Poly-B Belt, part number 03G903137B. This multi-ribbed serpentine belt is responsible for driving the alternator, which generates electrical power for the vehicle's systems and recharges the battery. Made from durable rubber and composite materials, it weighs 0.109 kg. Using a genuine OEM drive belt ensures the correct length, tension, and material composition for optimal power transfer and resistance to wear, preventing premature failure and maintaining critical accessory function.