For ease of adjustment UMI has designed our Ultimate Arms with on-car adjustability. You can easily make pinion angle adjustments in the garage or at the track; it's as simple as loosening two jam nuts! Using UMI's unique chromoly on-car adjuster, simply turn the adjuster with the control arms on the car to quickly lengthen or shorten the control arm length. Pinion angle adjustments are a must when wanting to lower your track 60-foot times, increase traction and reduce unwanted wheel hop. Our QA1 Teflon lined spherical rod end design allows for a bind free operation, making a great upgrade for both your track and auto cross driven car.