"Through on-track testing and in-house dyno evaluation, this entire product line has been treated to improvements. Each aluminum PRO Twin Tube Shock is carefully hand-built and comes with a serial numbered dyno graph. PRO Shocks carries all of the popular valving combinations and custom valving options are available. Call PRO Shocks for details. • Optimized low speed control for the ultimate in driver feel. • New and improved shock oil for fade free performance. • Low friction steel bearing rotates freely and withstands high temperatures. • Steam treated piston "