Description: Constructed of aluminum alloy materials, anti-rust, non-deformation, wear-resistant, high performance of durability. The -sliding sprocket features tooth profile with contoured shifting gates for clear and smooth shifting even under load. Mountain flywheel, hollow design, super high strength, lead chain slot and mud hole design, light weight, easy to clean. Material: High Pressure Steel Plate, Aluminum Alloy Holder Optional model (Speed&Teeth): 9S 11-42T, 10S 11-42T Specification: 9 Speed 11-42T: 11-13-16-20-24-28-32-36-42T 10 Speed 11-42T: 11-13-15-17-21-24-28-32-36-42T Package Includes: 1 Piece Bicycle Freewheel Note: The real color of the item may be slightly different from the pictures shown on website caused by many factors such as brightness of your monitor and light brightness.