PR0 TAPER COMBO KIT - Race Spec Front & Black Rear Sprockets & 520XRC X-Ring Chain - 520 x 120 Links. Race Spec MX Front Sprocket. Race Spec MX front sprockets have been CNC machined and internal broached to precise tolerances from case hardened core refined chromoly steel. Computer designed to ensure precise fitment and optimal weight savings while being perfectly balanced to allow minimal chain drag for maximum horsepower transfer without compromising strength. Finished with our proprietary coating process to further reduce wear and corrosion result in a front sprocket that is unparalleled in the market. Core refined 655M13 nickel-chrome-molybdenum alloy steel. Lightening holes to reduce rotating weight. Self-cleaning mud grooves to prevent dirt build up. Pro Taper Race Spec Aluminum Rear Sprocket. Race Spec aluminum rear sprockets have been precision CNC machined to the strictest of tolerances from the highest quality alloy that has been specially formulated for off-road motorcycle sprockets. 7075-T6 Heat Treated Aluminum. Lightening window pattern to achieve optimum balance of weight and strength. Precision CNC machined to strictest of tolerances. Exclusive Pro Taper angled mud groove design every tooth on both sides. CNC machined edge chamfers and inlay for subsurface Pro Taper sticker location. Countersinks to concentrically locate sprocket. Pro Taper 520XRC X-Ring Chain. Pro Taper chains are manufactured with lightweight, ultra high strength chromoly steel alloy for added performance and durability. Proprietary XRC-ring technology that was tested exclusively to handle the extreme temperatures and conditions of off-road riding & racing + 520XRC - Designed for up to 750cc applications. 8500 lb. tensile strength. FEATURES: Premium gold series motocross chain. Lightweight, ultra high strength chromoly construction. Replacement master links available.