Genuine OEM Hyundai Belt Tensioner, part number 2528104501. This critical component is responsible for maintaining the correct tension on the engine's accessory drive belt, ensuring consistent power delivery to components like the alternator, power steering pump, and air conditioning compressor. It weighs approximately 1.113 kg and measures 0.16m in length. Using a genuine OEM belt tensioner ensures precise spring calibration and durable bearing quality, preventing premature belt wear, noise, and potential accessory failure.