Renthal UltraLight Rear Chainwheels are CNC machined from 7075 T6 aluminum to extremely tight tolerances, 66% lighter than steel. Computer engineered and tested to ensure a precise fitment, concentricity and load dispersion with tooth profiling to provide maximum power transfer. A combination of high strength base material, cutting edge manufacturing methods and exceptional hardwearing surface treatments its clear to see why Renthal's light weight all aluminum rear sprockets can be found on the rear wheels of many factory race team machines.