Fox’s IFP-R shocks use an Internal Floating Piston (IFP) to separate the oil from the pressurized nitrogen compartment. As the shock compresses, the oil displaced by the shaft presses against the IFP, and the nitrogen charge behind it keeps the oil under pressure to avoid cavitation. While compression is not adjustable, a small knob at the bottom of the shock unit adjusts rebound by controlling oil flow around the main piston valve. When the needle is closed, all the oil flows through the main piston valving, creating the maximum damping forces for this particular tune. When the needle backs away, the jet port is open, and oil is allowed to flow through the shaft, bypassing the valving, and thus creating less damping. Preload and sag are easily adjusted at the top of the shock, and numbered markers make these adjustments quick and precise.