PR0 TAPER COMBO KIT - Race Spec Front & Rear Sprockets & 520MX Chain - 520 x 120 Links. Race Spec MX Front Sprockets. Race Spec MX front sprockets have been CNC machined and internal broached to precise tolerances from case hardened core refined chromoly steel. Computer designed by engineers to ensure precise fitment and optimal weight savings while being perfectly balanced to allow minimal chain drag for maximum horsepower transfer without compromising strength. Core refined 655M13 nickel-chrome-molybdenum alloy steel. Internal broached and precision machined to exact tolerances. Lightening holes to reduce rotating weight. Self-cleaning mud grooves to prevent dirt build up. Specially formulated coating to retain strength and aide in wear resistance. Race Spec Aluminum Rear Sprockets. 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. Engineer designed 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 520MX Chain. Designed, tested and produced with the highest level of Pro Taper quality. Our gold series chains are purpose built for today's demanding 4-stroke bikes & ATV's. Pro Taper chains are manufactured with lightweight, ultra high strength chromoly steel alloy for added performance and durability. 520MX - Designed for 125cc to 530cc applications. 8800 lb. tensile strength. Premium gold series motocross chains. Lightweight, ultra high strength chromoly construction. Replacement master links available