Supersprox - MX Steel Rear Drive Sprocket (RFE-457-51-BLK)Developed on the race track, to give longer system life and high performance for all street bikes. Using CAD Designed and CNC Laser cutting, to ensure an exact fit on the wheel. Made to Supersprox high quality standards and include our exclusive (2xZink) anti corrosion black finish. The will last 3 longer than any aluminium sprocket. One of the lightest steel sprocket. With the factory styling, you are not compromising on design.