LCD display with automatic backlighting lets you view the latest exercise data anytime. The built-in sensor wakes up on movement and enters standby when stationary for convenient, energy efficient use. Three in one system: wireless speed meter, horn controller and signal lamp all in one unit. It includes a 4000 mAh main battery to power the device and wireless speed measurement, and a 120 dB horn for audible alerts. In addition, a separate 2000 mAh lithium battery powers a three color tail lamp with 46 high brightness LEDs and switchable colors to improve nighttime visibility. Waterproof design reduces wiring clutter on the handlebars and provides rain resistance. It should not be submerged or used in heavy rain or storms, but it handles normal rain exposure. Tracking distance and speed over time works with most bikes including road, mountain, folding and standard bicycles. Note that a sensing distance of 5 mm between the probe and the magnet is required for accurate speed readings. Specifications and package: product weight 290 g. Package includes lamp meter unit, sensor, magnet transmitter, horn controller, cable ties, extended front bracket, and three color tail lamp.