whip on driveways, bumps & dips. This new Motion Control Unit is designed specifically to help vehicles with existing air suspensions. It responds instantly to compression force introduced by roll, sway, or bounce on the spring of your air suspension. Each unit operates independently both front & back and on each side of the coach. These units act like valving found in many shock absorbers. They produce a smoother, stable ride. | Hendersons Line-up SuperSteer Motion Control Unit, One-Quarter - Over 30,000 GVW