The AT4X Spec DSSV Shock System is designed and tuned specifically to deliver exceptional performance in a variety of scenarios - from technical rock crawling to tight two-track trails or hgh-speed desert running to daily driving. These 40mm Multimatic DSSV™ Shocks included in this system employ spool valve technology and offer increased precision for enhanced ride and handling performance both on- and off-road. Additionally, they provide up to a 2-inch increase in front suspension travel and up to a 1-inch increase in rear suspension travel. Enhancements from stock Trail Boss shocks include an 18mm diameter front rod and a 16mm rear rod to accommodate higher side load, advanced design seals to handle high shock temperatures, three separate spool valves to control damping and three connected chambers for fluid flow. Compatible with 2019+ Sierra AT4 models or vehicles equipped with the Performance 2-Inch Suspension Lift Kit (sold separately). Installation by an authorized dealer is recommended. The system includes complete front shock module assemblies, rear shocks, steel leaf springs and installation hardware.