Long Working Time: The 4000mAh high-performance rechargeable battery provides long-lasting freshness. The mini fan can work from 6 to 15 hours according to different speed levels. 3 Adjustable Speeds & Silent: The hand fan has 3 different wind speeds: soft / medium / strong. Choose the appropriate fan speed by pressing the power button repeatedly. The high quality motor inside the mini fan produces high power but low sound, quiet enough for studying, working and sleeping. The three-speed personal fan gives you more choices in different temperature environments. Portable and Compact Fan: The mini hand-held electric fan is small and exquisite, the mini fan is easily stored in a bag. USB fans are perfect for outdoor activities and travel, or place them on the desk. RECHARGEABLE FAN AND CONVENIENT CHARGING: The desk fan is equipped with 2 high capacity 18650 rechargeable batteries, it is compatible with all USB output devices and comes with standard USB charging cable, it can both work with or charge by 5V output adapter , a USB charger, laptop, computer, power bank and other USB devices. The portable fan is strong and durable to use. A wide range of applications: equipped with a round silicone base, which increases the friction with the contact surface. Not only can the fan be placed on the table when you sleep, work, eat at home, in the office or at school, it can also reduce vibration noise.