2005-2007 Super Duty 4x4 Heavy Duty Full Progressive Leaf Spring Kit - 1" Lift (CS-FFSP-LVL-05-HD)Description These Heavy Duty Full Replacement Leaf Springs are designed for those with constant 1,000lbs in the bed. They operate the same way as standard leaf springs when loaded. If the bed of your truck is empty, they are quite rigid. They provide 15" of increased wheel travel, 1" of rear lift, and smoother suspension cycling over terrain without lift blocks. These leafs feature a 9 leaf main and a 3 leaf overload for less jarring, more mobility in