Description: - This bike cassette cog made of high quality aluminium alloy material with anti-rust plating- high strength, strong and solid for long time using. - The set includes 5 pieces spacer, flywheel cover, and 1 piece flywheel for convenient using. - This flywheel is compatible with 7-10 Cassette flywheel. Please choose 7-10 chain to install. - Teeth: 19T. - Lightweight won' more burdens to your bike and scientific design increases area to protect hub body.Specification: - Material: Aluminum Alloy - Size: 19TPackage Includes:1 Set CassetteNote:1. Please allow slightly error due to manual measurement.2. Due to the difference between different monitors, the picture may not reflect the actual color of the item.3. Wish you a wonderful on-line shopping!