Genuine OEM Jaguar Accessory Drive Belt Tensioner, part number AJ813574. This assembly is crucial for maintaining the correct tension on the engine's accessory drive belt, which powers components like the alternator, power steering pump, and air conditioning compressor. It features a durable metal housing and a robust pulley. Weighing approximately 0.97 kg, this tensioner ensures consistent belt pressure. Choosing a genuine OEM tensioner guarantees precise spring calibration, durable bearing quality, and correct alignment for optimal belt life and accessory function.