The B8 8100 (ZoneControl R DSA) reservoir shock absorber is an adjustable large bore 60mm (2.65" OD) direct fit solution for lifted trucks and SUVs. Click adjuster knobs allow easy and precise Dual Speed Adjustment of both low and high speed compression to tailor your ride to any surface. ZoneControl R is a revolutionary double piston technology delivering position sensitive rebound damping which eliminates harsh suspension top-out events and the need for an external limit strap. Each B8 8100 (DSA) offers a unique remote or piggyback reservoir solution for an easy, hassle free installation. These shock absorbers feature a monotube design for consistent fade free performance and utilize velocity sensitive digressive valve settings which are tuned for each specific application. The large 60mm piston design offers more comfort and control in all driving conditions. The Bilstein B8 8100 (ZoneControl R DSA) offers unmatched levels of adjustable ride comfort and control.