Review on Waterproof Bicycle Speedometer Wireless Bike Odometer with LCD Display for Real-time Speed Tracking - 2 Pack Multi-functions Cycle Computer for Outdoor Cycling by Shree Carmean

First, the green backlight image is not clear. There is no backlight and is not visible at night. Second, the installation instructions are incomplete; There are more steps than the instructions indicate, namely blinking 20-40-60-80, which has no obvious meaning. Third, the calibration needs to be corrected, it's about 20% off the distance for the correct wheel circumference. All of which explains that this is a very affordable $10 wireless 'bike computer'. Edit: One of them broke after only 2 months. The right button no longer works.