Fusion Dual Rear Sprocket. Special hardened and nickel coated steel outer ring. Will outlast an aluminium sprocket up to 3 times. 50% less weight compared to a normal steel sprocket. Aircraft-grade 7075-T6 aluminium carrier. Precise manufactured outer ring and carrier interlock permanently using a specialized heat-shrink procedure. Carrier is colour anodized coated for extra durability. CAD designed, CNC machined and laser cut using state of the art technology. Engineered and manufactured in the Netherlands