EXERCISE REST TIME,CROWDED CONCERT SCENE,MUGGY AIR AGAIN,WILL BE ABLE TO GIVE YOU A STEADY STREAM OF CONVEYING COOL WIND,BRING A TRACE OF COOLNESS ,YOU ARE NO LONGER WORRY ABOUT SUCH HOT WEATHER.IT IS OPERATED BY USB AND ALSO BY BATTERY.YOU CAN ADD WATER AND FRAGRANCE FOR MORE COOLING AND FRESH EFFECTS OF YOUR ROOM.