Air Lift SMARTAIR II leveling systems utilize a unique, non-contact height sensor to detect when your vehicle is not level. Then, the systems automatically inflate or deflate your air springs to bring you back to the perfect ride height. Air Lift offers two paths–single and dual. The single path allows for the inflation of both air springs at the same rate at the same time, while the dual path permits the inflation of each air spring independently to different pressures. The SMARTAIR II systems require no lines or controls to be run into your cab.