Genuine OEM Volkswagen Chain Sprocket, part number 03E105209S. This sprocket is a crucial component within the engine's timing system, designed to mesh with the timing chain. It plays a vital role in synchronizing the rotation of the crankshaft and camshafts for optimal engine performance. It is identified as number 5 in the diagram. Genuine OEM chain sprockets are manufactured with precise tooth profiles and hardened surfaces for maximum wear resistance and accurate timing.