OPOLAR 10400mAh Battery Operated Fan, Portable Handheld Fan with 10-40 Hours Working Time,3 Setting, Strong Wind,Foldable Design, for Travel, Hurricanes, Camping and Outdoor Activities[Working Hours Duration]: This fan can work between 10 to 40 hours depending on its speed. Three times longer battery life than the average ones. [Strong Airflow and Foldable Design] speed 1 with 2400 RPM, speed 2 with 3100 RPM, speed 3 with 3600 RPM, has strong airflow to keep you cool. The foldable design makes it easy to be carried and stored. [DC Brushless Motor, Adjustable Tilt] Using energy saving DC motor, up to 20000 hours working duration.