Item Name: Bicycle Flywheel Material: Aluminum Alloy,Chromium Molybdenum Steel Size Details: Size: 12cm x 12cm x 6cm/4.72" x 4.72" x 2.36" (Approx.) With hollow mud drainage design, which can effectively reduce the load without affecting the overall strength of the flywheel. The silver surface looks exquisite and luxurious, which is no fading with electroplating, it is lightweight and portable with hollow design. Made by aluminium alloy and steel material, the product is sturdy, anti-rust and anti-corrosion. The length of this product is 12cm, width is 12cm, height is 6cm. It is suitable for mountain bikes. This product can compatible with the transmission systems of most major mountain. 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 Flywheel(Inculded a Flywheel Cover) 1 x Extension Tail Hook