Rear Ultralight Sprockets. Manufactured to extremely tight tolerances from a special material developed to withstand the stress of Supercross, Motocross and Enduro. 7075-T6 aluminum alloy rear chainwheels are 66% lighter than steel, yet incredibly durable. Advanced tooth profile, concentricity and accuracy of fit provide maximum power transfer and long life. Combination of high strength base material and hardwearing surface result in significantly increased chainwheel life. Self-cleaning mud grooves help prevent dirt build-up. Chainwheel Sprockets Rear 36-Tooth