Polaris RZR XP 4 Turbo S SuperATV GDP 4" Portal Gear Lift - Cast Housing 30% Gear Reduction. FITS: POLARIS RZR XP 4 Turbo S 2019–2021, POLARIS RZR XP 4 Turbo S Velocity 2019–2021. If you like to bury your machine deep in mud with huge tires and huge torque, there is a 30% gear reduction for that. GDP Portal Gear Lifts don’t put you in a box—they make what you’re already doing better. With the gear reduction in the hub, it makes life easier for the entire drivetrain before it. Your axles maintain factory geometry and work less. Your axles, prop shaft, differential, and transmission are under less stress. That means longer lasting components, and a lift that doesn’t destroy your machine. Cast aluminum housing. Cool, quiet, precision ground gears made from 9310 alloy billet steel. 1.5 in. diameter 4340 hardened steel drive shaft. Housings use Thermo-Tork® gaskets that don’t let anything through. Universal hub fits all major bolt patterns. Gear reduction reduces stress on your drivetrain. 4" Portal Gear Lift Includes: Assembled portal hub boxes complete with 9310 gears, seals, output shaft, Thermo-Tork® gaskets, and thrust bearings. Universal hubs and precision-ground stainless steel slotted rotors with lugs. Specialized steel alloy backing plates. Steel caliper mounting plates. Caliper adapter plates. Steel steering arms. Extended brake lines. All required hardware, including recessed castle nut socket. Frame Stiffener / Gusset Kit is recommended (#202231). Wheel Requirements: 14" or larger wheel required. Wheels cannot exceed 5" backspacing. Not compatible with dual beadlock wheels. Special Notes: Polaris RZR XP Turbo S Portal Gear Reduction Recommendations: Max Tire Size Required Suspension Setup Recommended Gear Reduction Up to 36" Stock 15%. 39" 1.5" Forward Offset A-Arms 15%. 39" 3" Lift Kit 15%. 41" 1.5" Forward Offset A-Arms & 3" Lift 30%. Gear reductions listed are general guidelines to maintain factory top speed. Installing a larger than recommended gear reduction will result in extra torque and lower top speed.