ICON Vehicle Specific (V.S.) 2.5 Aluminum Series shocks are designed and built to give your vehicle outstanding performance off-road and a smooth ride on the street. These shocks are configured specifically for each application in both length and damping tune. Like all ICON'S Shock Absorbers, V.S. 2.5 Aluminum Series shocks are 100% rebuildable and 100% revalveable. For piggyback and specific remote reservoir applications ICON'S unique use of a 6061 billet aluminum manifold a few inches below the top cap of the shock creates an internal Bump Zone that when used creates an additional 20% of damping force. This additional force helps prevent harsh bottom outs and controls the suspension when compressing at high velocity. The ICON CDC Valve is an externally adjustable valve that restricts oil flow into the reservoir which creates 10 levels of compression damping force ranges. If you are looking for a more user defined tune, consider looking into the Omega Series bypass shocks. 2007-2021 TOYOTA TUNDRA REAR 2.5 VS PIGGYBACK CDCV SHOCK PAIR