The JET Underdrive Pulley Set reclaims lost horsepower and mileage by reducing the drag placed on the engine to drive accessories like air conditioning, power steering, and water pump. JET Pulleys slow down these accessories to allow the engine to turn with less effort without any adverse effect on the operation of A/C, power steering, charging or cooling systems. Installation consists of simple bolt-on replacement of the stock pulleys. Kits include pulleys, hardware, complete instructions, and part number for new serpentine belt* (most kits will require use of smaller size belt). Note: Belt is not included with kit, and type/quantity of pulleys will vary per application