Features 1、Multi Layer Plating and Anti Rust Treatment: High tension steel plate nickel chromium plating, multi layer plating and anti rust treatment, high accuracy tooth ratio. 2、Concave and Convex Tooth Design: Concave and convex tooth design, make the speed change more gliding, weight reduction, and strong compatibility. Suitable for road bikes. 3、Hollow Technology: Adopts hollow technology, can effectively and easily reduce the weight, so that riding easier, and more gliding. 4、Runs Smoothly: The flywheel rotates smoothly and has no noise, and can well ensure that it is closely connected with the wheel hub of the bicycle and runs smoothly. 5、Simple Operation: Simple to operate, easy to use, easy to install and disassemble. Without any difficult requirements even though you use it for the first time. Item Type: 9 Speed 30T Cassette Freewheel Weight: Approx.369g / 13.0oz Speed Ratio: 11-13-15-17-19-21-23-25-30T Material: Nickel Chrome Steel Applicability: Suitable For Road Bikes and Folding Bicycles Package List 1 x Flywheel 2 x Sprockets 1 x Flywheel Cover