Features1Strong and Durable: Made of CNC aluminum alloy, light weight, rust resistant, corrosion resistant, and anodized. 2Two Wheel Models: Guide wheel adopts a circlip fixed structure, which is compatible with the guide chain wheel and the tension wheel. 3Strong Compatibility: To meet different sizes, 10 teeth are suitable for 8, 9, 10, 11 speed rear derailleur, and the outer diameter of the installation shaft is compatible with 4, 5, and 6mm. 4Smooth Rotation: Zirconia ceramic balls are used, which are self lubricating and maintenance free. At the same time, the transmission efficiency is higher and the riding is labor saving. 5New Design of Circlip: With the new fixed structure of circlip, it solves the problem of chain jam and guarantees smooth speed change and stable operation of the rear derailleur.SpecificationItem Type: 10T RearDialGuideWheelColor: As Pictures ShownWeight: Approx.9g/0.3ozMaterial: Aluminum Alloy + Ceramic BallPackage List1 xRearDialGuideWheel2 x Reducing Sleeve