The Air Lift Load Controller II is an on board air compressor system for your vehicle. It attaches to your existing air shock system to maintain the air pressure. It levels the vehicle via a dual path, so both sides can be set to separate pressures (useful if you haul an uneven load). This On Board Compressor Kit also includes a new wiring harness for faster and easier installation than previous versions of this item. The gauge and integrated 5psi low pressure sensor makes sure that the compressor kicks on automatically when needed. Two year Manufacturer warranty.