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. Made in Europe