Sprotsrain SD-573C LCD Computer Odometer Sport Cycle- Waterproof Outdoor Wireless Speed Meter Multifunctional - for Mountain Bike Cycling (Black) It is made of plasticwired , Portable, compact, light and easy operation, multi-function with LCD. Wireless heart rate, Automatic wake-up wire key Multi Functions record cycling data from several aspects, all-round; and truly, scientifically arrange cycling life It has many functions as SPD, Maximum Speed. Average driving speed. And the average speed of contrast prompt. Every minute wheel run circle number).Odometer (Total Distance). DST - Trip Distance, etc. Computer Odometer Sport Cycle has Waterproof functions with back light. You will not worry it will out of work in the rain. Easy view of the maximum speed, average speed, total riding time, total riding distance and rotations per minute of the wheel. Maintenance alert. Instant heart rate (beats per minute). Maximum heart rate (beats per minute) stopwatch feature and alert feature for bicycle maintenance. Length unit options of kilometer/mile, Imported sensors to provide stable performance and accurate speed. Real-time indication of acceleration or deceleration for easy control speed.