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