High-quality material: 8 wheels are made of high-strength metal, which is anti-rust, non-deformable, wear-resistant and durable. Meets quality control standards and is reliable to use.Good tool: fast driving and labor-saving. Reliable and suitable for mountain bike cassettes. High performance, reliable performance, easy installation.Excellent performance: High-precision threads a tight connection with the bicycle hub and operation. It can that the chain turns smoothly without too much noise. Good replacement, direct replacement for the old or defective one.Quality Assurance: The bicycle flywheel has undergone quality inspection to safety and reliability. Professional after-sales production, quality standards. Good quality can provide a for your life.Colour:As ShownMaterial:steelSize:15.5 x 15.5 x 9 cmPackage Contents:1 x bicycle spinning freewheelOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.