Small size, light weight, stylish design . Easy to installThis Wireless Multi Functional Cycle Speedometer is easy to install, and allows accurate measurements of your work rate/progress. The included instructions will guide you through the following Functions.Multi Function: Speed Comparator,Average Speed ,Maximum Speed & Relative Speed,Riding Time,Riding Distance ,Total Riding DistanceSuitable for Tire Size: 700cx38mm, 700cx35mm, 700cx32mm, 700cx30mm, 700cx28mm, 700cx25mm, 700cx23mm, 700cx20mm, 700cTubulari, 650cx23mm, 650cx20mm, 27x1-1/4, 27x1-1./8, 26x2.3, 26x2.25, 26x2.1, 26x2.0, 26x1.9/1.95, 26x1.75, 26x1.5, 26x1.25, 26x1.0, 24x1.9/1.95, 20x1-1/4, 16-2.0, 16x1.95, 16x1.5Waterproof Computer Metric,Imperial Speeds (mph/kph)Package included:1 X Wireless Bike Computer Speedo OdometerNote:Light shooting 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.