Fox Factory IFP Monotube Shocks For Harley FXR FOX's IFP design, combined with vehicle specific damping and linear spring rates, gives you a confident connection to the road while soaking up the bumps, mile after mile. With an internal floating piston to separate the nitrogen gas from the shock oil, the IFP shock will maintain damping control no matter how long you ride. Features: Gas-charged mono-tube, with Internal Floating Piston (Ifp) 1-1/2 6061-T6 aluminum type III hard anodized body Spring preload setting guide marks Fully rebuildable and revalveable Advanced high-flow, deflective disc velocity-sensitive damping 1/2 low friction, super-finished hard chrome shaft Sold as a pair