Features1This is a bicycle or tricycle general mechanical speedometer, it is a high-quality bicycle equipment made of durable aluminum alloy. 2It works for 26/27.5/28/29 inch bikes only, be sure to check your bike size before you buy it. 3Pure mechanical bike computer, not only has good quality, but also has accurate data. 4Accessories are complete and easy to install, you can do it by yourself without any effort. 5The must instrument you should need for your bike journey, and you'll find it useful.SpecificationMaterial: aluminum alloySize: about 11 * 8 * 8cm/4.3*3.1*3.1inchFeatures: pure mechanical stopwatch, good quality and accurate dataApplication: Suitable for 26, 28, 29, 27.5 inch bicyclesPackage List1 * Bicycle Speedomete