Moose Racing Aluminum Rear Sprocket - 50T 1211-1442The 7075 T 651 aluminum we use for these sprockets receives an extra tempering which reduces distortion and provides optimal thickness vs. typically thinner 7075 T 6 sprockets 100% machined, no stamping or grinding Optimal tooth thickness results in maximum tooth and chain contact We leave the cleaning grooves out of our sprockets, because more aluminum contacting your chain means longer chain and sprocket life Moose Racing rear sprockets come