Genuine OEM Audi Engine Belt Tensioner, part number 06F903315. This crucial component is responsible for maintaining the correct tension on the engine's accessory drive belt, ensuring the reliable operation of components like the alternator, power steering pump, and air conditioning compressor. Constructed from durable metal with a robust pulley, it weighs 1.103 kg. Choosing a genuine OEM belt tensioner guarantees precise tensioning force, smooth pulley operation, and long-term durability, preventing belt slippage, noise, and premature wear of engine accessories.