Genuine OEM Volkswagen Belt Tensioner, part number 059145201F. This critical component is responsible for maintaining the correct tension on the engine's accessory drive belt, which powers essential systems like the alternator, power steering pump, and air conditioning compressor. It is typically mounted on the engine block. Constructed from robust metal with an integrated pulley and a hydraulic damper, this assembly weighs 0.99 kg and measures approximately 0.26 meters in length. Installing a genuine OEM belt tensioner ensures precise belt alignment and consistent tension, preventing premature belt wear, slippage, and potential damage to engine accessories.