The ICON Vehicle Dynamics 2005-2023 Ford F-450 and F-550 Super Duty 2.5" coil springs are designed for drivers demanding the ultimate in performance and ride quality, while allowing for increased wheel travel (when used with ICON shocks) and the fitment of larger tires. The ICON Ford Super Duty coil springs provide 2.5" of lift height and feature a dual rate design optimized for use with trucks equipped with diesel engines. The dual rate design allows for a softer initial rate for superb on-road comfort and a firmer secondary rate that increases during compression for excellent bottoming resistance and off-road performance. Caster correction cams are also included to ensure proper caster angle with the new, taller ride height. Like all ICON coil springs, they feature a lifetime guarantee against sagging/breakage to produce confidence in knowing that you have the best suspension products available for the 2005-2023 Ford F-450 and F-550 Super Duty.