The all new Non-Adjustable Black X Series has been designed based off of driver input and on-track performance. Through racing applications and in-house dyno evaluation, PRO has developed the ultimate non-adjustable shock. Each PRO Twin Tube Shock is carefully hand-built and dyno sheets are included with every shock. PRO Shocks carries all of the popular valve combinations. The Non-Adjustable Twin Tube Shocks X Series in Smooth finish is targeted at Sprint Car applications.