Features: Positive and negatives toothed guide wheel chain transmission efficiency, effectively reduce frictions, improve speed response, and enhances cycling performances. Make from aluminum alloy, light weight while maintaining wear and corrosions resistance, ensuring long terms use. There is convenient adjustment mechanism, can quickly adjust according to their personality needs to obtain the best cycling experiences. Ceramic Ball Bearing, anodizing process, bright color and beautiful. Suitable for 6/7/8/9/10/11/12 speeds derailleur systems. It comes with inner diameter 4mm bushing and inner diameter 5mm bushing. Specifications: Component: Aluminum alloy Type: 10T/12T/14T/16T Colors: Black/02/Blue/Red/Pink/01 Weight: 10T: 8.8g/12T: 11g/14T: 14.50g/16T: 18.50g 10T Size: about 49x8mm/1.93x0.32inch 12T Size: about 52x8mm/2.05x0.32inch 14T Size: about 59x8mm/2.32x0.32inch 16T Size: about 67x8mm/2.64x0.32inch Package Includes: 1pc Bike Ceramic Pulley note: Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item.