Renthal Ultralight Rear Sprockets are CNC machined and drilled from 7075 T-6 Aluminum to offer a lightweight, strong and wear resistant alternative to the standard steel sprocket. Designed with self-cleaning grooves for quicker dispersion of abrasive materials and combined with the wear resistance of the 7075 T-6 allows for a comparable life span to steel sprockets. 66% lighter than comparable steel sprockets. 7075 T-6 aluminum alloy. Self-cleaning chain grooves. Fits OEM bolt pattern.