ICON's 4" system provides great off-road performance, using the same technology that's used on off-road race trucks, and allows clearance for 35" tall tires. Icon starts with ICON Series Progressive Rate Leaf Springs that have a lifetime guarantee against sagging. Next, they add their box kit which helps retain factory steering geometry. To get the best ride quality and performance, adding the ICON Series Mono-tube shocks is ideal. All of the components in the system is backed by the ICON Life-time Warranty.