Here is a little more info on how you use it...
To set your ride height to exactly the setting you want, you do as follows:
In picture 2, loosen the locking screw and move up or down until the platform is at the desired ride height. Do the same for front and rear.
Lower the truck onto the gauge with full running gear and work the suspension up and down. The soft springs on the gauge will allow you to cycle your suspension and come to your resting ride height. Adjust the preload of your springs until the ride height is set.
You can also check your ride height by loosening the locking screws and lowering the platform lower than your ride height. Cycle your suspension and then raise the platform until it touches the chassis of your truck.
By knowing your ride height, you can more accurately make changes like changing springs, and still keep the same ride height or change it. The ability to change a setting, see what it does, and change it back if need be is priceless.
Pro-Line Racing team driver.