Features: The high performances designs of folding bike single speed flywheel provide fast cycling speed while saving effort.Folding bike single speed flywheel have smooth turn action no much noise.Make of aluminum alloys and steel, strong, Rusts resistant and wear resistant.It have high accuracy thread machining to ensures a tight connection with the bike wheel andsilky running.It can directly replaces old and broken accessories, ensuring the normal of your bike.Specifications: Materials: Aluminum alloys, steelStyles: 10mm hole diameter/12mm hole diameterSize: as shown in the picturePackage Includes: 1pc Single Speed Cog Sprocketnote: Please allow 1-2cm errors due to manual measurement, make surely that you not mind before order. Due to difference between different monitors, the picture may not reflect the actual color.