welcome to my store. Hope you have a pleasant shopping trip! Features:1. The positive and negative teeth of the rear derailleur ceramic guide wheel are designed to fit more closely and reduce the lateral virtual position, which can shorten the speed change response time and improve the speed change performance.2. With a reducing sleeve, the compatibility is stronger, the original diameter of 6mm can be converted to 4/5mm through the reducing sleeve, and the rotation is flexible3. Silicon nitride bearing, high-precision force is not easy to deform, high temperature and low temperature resistance, cold resistance, wear resistance, high transmission efficiency, smooth speed change, more labor-saving riding4. Deeper tooth marks to reduce chain loss, deep tooth guide wheel, synchronized with the chain drive direction, smoother chain entry and dechaining, surface anodized treatment, wear-resistant, ceramic bearing, lightweight aluminum alloySpecifications:Material: aluminum alloy + ceramic bearingNumber of teeth: 12T 14TApplicable: 8/9/10/11 speedColor: black red goldPackage List:1PCSNotes:1. Due to the difference between different monitors, the picture may not reflect the actual color of the item. We guarantee the style is the same as shown in the pictures.2. Please allow 1-2cm slight dimension difference due to different manual measurement.