Precision CNC manufactured to extremely high tolerances from a high strength, specially enhanced 7075 T6 aluminum alloy. Unequaled accuracy of fit, tooth profile and concentricity for longevity and maximum power transfer. Maximum reduction of unsprung revolving weight at the rear wheel, through a choice of materials and design insures maximum power transfer. Renthal rear chainwheels are 33% lighter than steel yet incredibly durable. Hard anodized finish.