This backpack is equipped with dual-sided, 4 LED signal lights which will respond to signal received from remote controller, reminding passengers and drivers keep distance from you. Built-in 500mAh rechargeable battery. It can work 20-30 hours of continuous work after 3 hours full charging. Absolutely a perfect add-on for night safety cycling. Features: Dual-side, 4 Led signals, reminding passengers and drivers to keep a safe distance. Wireless control, mounting it on handle bar, free your hands, safe and convenient. Built-in 500mAh rechargeable lithium battery, easy to recharges from your computer or any device with USB port. 20-30 hours of continuous work after 3 hours full charging. Ultra light and ultra thin, easy to wear without adding extra burden. Perfect choice for running, cycling, mountaineering, hiking, fishing, cross-country and other outdoor activities. Specifications: Material: PC + ABS Color: Green Working Time: 20 - 30 hours Charging Time: 3 hours Battery: 4.2V, 500mAh Bag Size: 25.4 * 22.9 * 2.2 cm / 10 * 9 * 0.9 in Bag Weight: 460 g / 1.0 lb Package List: 1* Bag 1 * Wireless Controller 1 * Controller Mounting Base 1 * USB Cable 4 * Zip Ties 1 * Manual