Features1PRECISE CRAFTSMANSHIP: Crafted from 6061 aluminum alloy through a series of CNC milling, polishing, and anodizing processes, the ceramic rear derailleur pulley showcases a refined metal texture, with a lightweight hollow design for enhanced performance.2ENHANCED COMPATIBILITY: Featuring a new spring structure that prevents chain jamming, the 11 tooth design is suitable for 8, 9, 10, and 11 speed rear derailleurs, with an outer diameter compatible with 4, 5, and 6mm installation axles, ensuring smooth and silent rotation.3VERSATILE USE: Designed for both guide and tension pulleys, this pulley's spring fixed structure allows compatibility with both guide and tension pulleys, providing flexibility and convenience for a variety of setups.4SMOOTHLY ROTATION: Utilizing an oxidized zirconia ceramic ball, known as white ceramic, the ceramic rear derailleur pulley offers self lubricating easy maintenance, ensuring a smooth and seamless rotation experience.5IMPROVED TRANSMISSION EFFICIENCY: With a new spring fixed structure to prevent chain jamming, the ceramic rear derailleur pulley not only enhances pedaling efficiency but also guarantees smooth shifting and stable performance during rides.SpecificationItem Type: Bike Ceramic Bearing Pulley WheelMaterial:Ceramic,aluminumalloyPackage List1 x Derailleur Pulley2 x Reducing Sleeves