Ali Huang(TM) 20 Functions Outdoors Cycling Computer Bike Speedometer Odometer with Stopwatch / Calories / Backlights (Blue) 20 main functions, includes all vital functions for bike, cicyclem cycling Easy installation, no tools required. Ideal companion for your riding Durable and water resistant for use in all kinds of conditions. Easy to read, two-line LCD display with green backlight Apply for the wire diameter within0.2CM and Bicycle wheel circumference within 0CM-999CM (0-inch to 40-inch) Magnets installed in the spokes, make the distance of magnets and the sensor is less 5MM