Aluminum Rear Sprocket100% German aluminum using ISO 7075-T651 for these sprockets receives an extra tempering which reduces distortion and provides optimal thickness100% machined, no stamping or grindingOptimal tooth thickness results in maximum tooth and chain contactWe leave the "cleaning" grooves out of our sprockets, because more aluminum contacting your chain means longer chain and sprocket lifeMoose Racing rear sprockets come anodized in black or silver; select Moose Racing rear sprockets are available in blue, red and orange