Description: 【Application】Strong compatibility, very suitable for mountain bikes, road bikes, folding bicycles, city bikes, etc. It is an excellent accessory for your bicycle. 【Metal Structure】The bike freewheel made of high quality durable aluminum alloy steel materials, high strength, sturdy and durable, and long service life. 【Practical tool】The bicycle flywheel adopts free hub and the flywheel are integrated, with 2 built in bearings, hole diameter 12mm/0.47inch, high precision, excellent performance and stable and reliable. 【Easy to install】The bicycle flywheel sprocket is easy to install and use, which can provide you with a good experience. 【Replacement Accessories】Folding bike freewheel can replace the old or damaged accessories well and upgrade the overall performance. Specification: Material: Aluminum Alloy Steel 3 Speeds: Gear Ratio: 9-13-17T 5 Speed: Gear Ratio: 9-11-13-15-18T Size: 3 Speeds: 7cmx7cmx2.6cm/2.76inchx2.76inchx1.02inch 5 Speed: 7.4cmx7.4cmx3.4cm/2.91inchx2.91inchx1.34inch Hub Axle Outer Diameter 12mm/0.47inch Feature: The free hub and the flywheel are integrated, with 2 built in bearings Uses: Folding car speed change Package Includes: 1 Bike Freewheel Note: 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 online shopping!