New Portable Mini USB Fan - With Rechargeable Battery, Adjustable Speed, Rotation & Silence Best Quality Feature: The portable fan was very quiet. Solid structure, stable and reliable. Powerful by battery or USB, a variety of power sources. Portable clip anywhere, and you can also just use it on the base of the fan stand. Be free to lower or raise the air volume with stepless speed technology. Rechargeable battery. Different speed modes. Adjustable speed: you can adjust the speed from low to high as you likePower bank function and quiet operation4800mAh power bank mini fan for emergency or supply for mobile phone, MP3, iPod, etc. Frameless, it emits noise at 50db which causes no disturbance while working.