1.POWERFUL YET SILENT: With our newly advanced technology, our portable fans are able to generate up to 3200 RPM in the maximum speed setting while still maintaining a relatively quiet decibel, quiet enough to run in a library. 2.LONG TIME OPERATION AND USB CONNECTION:4000mAh(2x2000mAh) large capacity batteries provide 5-20 working hours duration (depend on different speeds). Batteries are rechargeable and irreplaceable(for safety). USB charging by a computer, laptop, power bank,USB Charger, cellphone adapter, car charger etc. This hand fan will work on 110 or 220 volts which can be carried to all over the world. 3.MULTIFUNCTIONAL FAN AND MINI SIZE:It can be desktop fan or handheld fan to satisfy your different needs with cool design, you can put the fan upright or diagonally on the table,also great for office.You can carry it with you easily when you go out for a picnic, shopping, traveling, camping, etc. It is small in size (3.4-inch wide and 6.3-inch long Weight: 6.1 oz) and can easily fit in your pocket, backpack, or beach bag. 4.FAST CHARGE AND ONE-KEY OPERATION: Fans gets charged in 3 hours only while other similar fans need 6 hours. The battery of this fan has been designed for the current input of 2A (others 1 A), which makes it get charged faster. Besides, It is easy to use this mini battery fan with only one button. Short press the button to turn on the fan, and press repeatedly to adjust the wind speed or turn off the fan. 5.DETACHABLE COVER:The cover can be detached easily by rotating lid gently and you can clean the cover blade or even the inner part as you wish.