Fox high performance synthetic suspension fluid is engineered to exceed the demanding conditions of modern suspension systems. It is formulated using the most advanced fully synthetic base fluids to provide consistent performance throughout extreme temperature conditions. The 10wt. Red Fork Oil employs a proprietary additive system that maintains a high IV and eliminates stiction, friction, and wear as well as protecting against foaming, seal-swell, oxidation, and corrosion. The 10wt. Red fork oil is designed to work in Fox’s FIT dampers. If you’re overhauling your FIT cartridge, this is what you want. If you’re only changing out the dust seals, you’ll need the 20wt Gold Fork Oil.