The Big Gun X Double Adjustable Twin Tube shocks are specifically valved for high horsepower drag radial tire equipped applications. Drag radial competitors require a unique valving package to control the rear suspension and properly apply the radial tire to the track. Superior traction is achieved through a high flow piston that delivers consistent performance, pass after pass. If you have 1,000 - 1,500 horsepower and are on a drag radial tire, this is the valving package you need to complement your race program. For quicker adjustments, mount your AFCO shocks upside down for unsprung weight savings and ease in accessing the rebound adjuster. Double Adjustable - broadest range of adjustment in industry. Big Gun X Valving - specifically valved for high horsepower applications: S/O, NPS, Ultra Street, and Quick 8.Great for BIG or SMALL tire door slammers. Rebuildable and revalvable.