Wireless MTB Bike Speedometer LCD Waterproof Bicycle Meter Computer Odometer Features: Auto Wake-up Function: Automatically wakes from sleep mode upon sensing vibration in the bicycle. Bright LCD display to easily view ride statistics. Multi-functions: Small size, light weight, wireless, waterproof design makes it convenient and durable. This bicycle computer measures speed, distance, and riding time. Exactly what any serious bicyclist or fitness fanatic needs to know for stats tracking. Day & Night Backlight : Provides backlight for easy viewing during dark hours. The backlight will automatically turn on when any button is pressed between 18:00 and 06:00. Please note the slight rattle sound from device is normal phenomenon, which results from the design of wireless automatic function. Easy to Install &Use: Simple installation that only takes a few minutes. Easy to navigate interface with only two buttons to access all measurements. Customizable to most common tyre sizes for accurate stats tracking. Applicable: Road bicycles, mountain bikes, folding bikes,and other common bicycles are compatible with this bicycle computer. Specification: Material: ABS + electronic components Dispaly: LCD display Size: 56mm*41mm*20mm Weight: 80g Power supply for Speedometer: 1*CR2032 button battery Power supply for sensor: 1*23A battery Package includes: 1 x Bicycle Speedometer 1 x Wireless Sensor 1 x Seat 1 x Magnet 4 x Plastic tie-wrap 1 x Elastic ring 1 x user manual"