SLS coil springs are a lighter weight steel spring with a lower un-sprung weight to improve performance compared to the standard FOX coil spring. They are also lighter than titanium springs at more affordable prices. The 35 mm/1.385" Internal diameter also fits DVO, MRP and X-Fusion shocks. - Internal Diameter: 35 mm/1.385" - Lower un-sprung weight of the SLS coil spring improves performance compared to the FOX standard coil spring - For riders that want the performance and light weight of an SLS spring with the added benefit of a matte color to match their rear shock