FOX SLS Rear Spring - 3. 5" Stroke The weight of a titanium at a fraction of the cost. Utilizing a thinner wire and less coils, FOX SLS (Super Lightweight Steel) rear springs deliver a light weight option for rear shock springs at a much lower cost than titanium version. They are also able to withstand higher stresses due to a proprietary surface treatment. These will fit all FOX coil shock and are available in 25lbs increments from 225lbs to 400lbs. Fox SLS Rear Spring Specifications : Stroke: 3. 5" Weight: 292g Spring Rates: 225lbs to 400lbs Compatible with all FOX coil shocks | Fox Racing Shox | Sls Rear Spring - 3. 5" Stroke 039-94-025 - 300 Lbs/in, 3. 65 Travel