This backpack is equipped with reflective strips and 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 12-15 hours of continuous work after 2.5 hours full charging. Absolutely a perfect add-on for night safety cycling. Features: 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. 12-15 hours of continuous work after 2.5 hours full charging. Ultra light and ultra thin, easy to wear without adding extra burden. Adjustable shoulder and waist straps to fit your body perfectly. Perfect choice for running, cycling, mountaineering, hiking, fishing, cross-country and other outdoor activities. Specifications: Material: Nylon + polyester Color: Yellow / Gray ( optional ) Working Time: 12 - 15 hours Charging Time: 2 - 2.5 hours Battery: 4.2V, 500mAh Bag Size: 24.5 * 24.5 cm / 9.6 * 9.6 in Bag Weight: 209 g / 7.4 oz Package Weight: 253 g / 8.9 oz Package List: 1* Backpack 1 * Wireless Controller 1 * Controller Mounting Base 4 * Zip Ties 1 * Manual