Pulley kits comprise matched sets of engine and accessory drive pulleys designed to optimize belt alignment and performance. These kits are utilized within the front engine accessory drive system, including components like the alternator, power steering pump, and air conditioning compressor. Kits often feature oversized pulleys to reduce belt speed and engine load, or undersized pulleys to increase it, altering accessory performance characteristics. Components are typically manufactured from aluminum alloy for weight reduction and efficient heat dissipation, and may include a dedicated tensioner pulley. Precise dimensional control and dynamic balancing are critical for smooth operation and extended belt life.