Description: Hollow design makes it drain and convenient for heat dissipation. High precision tooth design of the gear piece prevents the chain from falling off. The flywheel is anti-rust, non-deformation and wear-resistant, which makes it used for a long time. It is suitable for mountain bikes, folding bikes and other common bicycles on the market. Made of high quality steel and aluminum material, it is durable. The length of the product is 20cm, the width is 20cm, and the thickness is 5cm. It is suitable for road bikes, mountain bikes and so on. Item Name: Mountain Bike Flywheel Material: Steel,Aluminium Color: Black Speed: 13 Speed Teeth Number: 11T-46T Gear Ratio: 11-13-15-17-19-21-23-26-28-32-36-42-50T Features: Hollow, High Precision, High-tensile Size Details: Size: 20cm x 20cm x 5cm/7.87" x 7.87" x 1.97" (Approx.) Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 1 x Bicycle Freewheel