SLS springs are a lighter weight steel spring than the standard Fox spring. They are lighter than titanium springs at more affordable prices. The 35 mm/1.385" Internal diameter also fits DVO, MRP and X-Fusion shocks.Features-Internal Diameter: 35 mm/1.385"-Spring markings: 450 lbs x 2.9" Item Specifications-Spring Weight:450lbs-Stroke (ins):2.9-Material:Steel