Features: Suitable for 5-speed, 6-speed, and 7-speed models to meet the needs of different users. Using good-quality materials and accuracy craftsmanships to ensures a smooth shifting experiences, improving cycling efficiency and comfortable. After special treatments,excellent wear resistance and corrosion resistance, extending its service life and reducing maintenance costs. On the premise of ensuring strength, try to reduce the weight of the flywheels itself as much as possible and improve the flexibility of the entire vehicle. The structure is reasonable, ensuring smooth gear shifting and avoiding chain breakage or lagging, providing a better cycling experiences. Specifications: Color:Three Elections Dimension:8.7×8.7×2.1cm/3.42×3.42×0.82in 10.6×10.6×2.5cm/4.17×4.17×0.98in 11.5×11.5×2.9cm/4.52×4.52×1.14in Component:Steel toothed plate+aluminum alloys locking cover Package Includes: 1pc Multispeed Cassettes Flywheels note: 1.Please allow 1-2cm errors due to manual measurement, making sure that you will not mind before order. 2.Due to the differences between different monitors, the picture may not reflect the actual color.