Feature: 1.【NON‑DEFORMATION】The bicycle flywheel is resistant to high temperature, corrosion, rust, non‑deformation. Wide tooth ratio mountain flywheel, large tooth ratio flywheel, for single tooth disc. 2.【HIGH TOOTH SHAPE】Card type flywheel with high wear resistance, durability, impact resistance, high tooth shape, strong compatibility, so that more possibilities for riding, it's easier to climb a hill. 3.【HOLLOW DESIGN】Bicycle Freewheel Uses a hollow design, which is lightweight. While reducing weight, it can also increase speed. 4.【EASY TO INSTALL】Bicycle freewheel is easy to install, no adjustment is required, stable gears and accurate positioning are provided within the range. 5.【GREAT ACCESSORIES】Bike cassette is a great accessory for mountain bikes and road bikes, which is the favorite of cyclists. Specification: Item Type: Bike Freewheel Material: Chromium molybdenum steel Color: As Pictures Shown Weight: Approx. 544g 19.2oz Specifications: 10 speed 11 40T Small teeth: 11 T Teeth: 11 13 15 18 21 24 28 32 36 40T Black Big Teeth: 40T Wide tooth ratio mountain flywheel, large tooth ratio flywheel, for single tooth disc. It's easier to climb a hill Package List: 1 x Bike Freewheel