Genuine OEM Audi A/C Compressor Idler Pulley, part number 03C145276C. This pulley plays a crucial role in the engine's accessory drive system, specifically guiding the serpentine belt that drives the air conditioning compressor. It helps maintain proper belt tension and alignment, ensuring smooth and efficient power transfer. Weighing 0.6615 kg, this pulley is engineered for high rotational speeds and durability. Choosing a genuine OEM idler pulley ensures correct belt alignment, reduces vibration, and provides the factory-specified bearing quality for a long and quiet service life, preventing premature belt or component wear.