Genuine OEM Volkswagen Poly V-Belt Pulley, part number 03D903119D. This pulley is mounted on the alternator shaft and is driven by the serpentine or V-belt, causing the alternator to generate electricity. It is located at the front of the alternator assembly. Manufactured with precise dimensions and balanced for smooth, vibration-free rotation. Genuine OEM pulleys are crucial for maintaining correct belt tension and alignment, ensuring the longevity of the belt and the efficient operation of the alternator.