Genuine OEM Audi Belt Tensioner, part number 038109243M. This critical component ensures the correct and consistent tension of the engine's accessory or timing belt, preventing slippage and premature wear. It is typically located within the engine's belt drive system. Featuring a robust metal pulley and precision bearing, it weighs approximately 0.6904 kg. Installing a genuine OEM belt tensioner guarantees factory-specified tension, smooth rotation, and vibration-free service life, crucial for belt and engine component longevity.