When you lift your car to put on scales the front wheels camber in at the bottom. As you let the car down the wheels must move back out freely to equalize. If they can't, they will hold the chassis up slightly, preventing free movement and adversely affecting the weights you get. The result will be inconsistent readings, throwing your setup off. The front wheels MUST be allowed to move horizontally as freely as possible. Side Sliders relieve any horizontal bind by allowing the wheel and scale pad to roll sideways effortlessly and virtually friction free. You get more consistent wheel weights for the most accurate setups possible, time after time.

Rollers are made from a tough, low friction polymer
Install under Left Front wheel (it has the most camber change)
3 spacers are included to re-level your setup
Use on any smooth floor surface
2 Side Slider systems are available for independent rear suspensions