True high performance front suspension is finally available for the HD 49mm front ends. Progressive Suspension has gone back to the drawing board and created a state of the art Fork Cartridge Kit designed to outperform everything on the market. Our new asymmetrical design places a preload adjuster over a progressive rate spring in one leg and aluminum bodied, sealed cartridge damper on the other. The result is superior damping and ride control combined with tunable preload and a new benchmark f or high performance suspension.