Rechargeable via USB: With built-in 1200 mAh high-performance lithium batteries, the USB rechargeable fan can work 2 to 3 hours when fully charged. This mini fan is compatible with all USB ports, so you can charge it from any USB device. Fast cooling and removable fan guard: The USB fan has a 4-blade design that maximises airflow for a cooler and smoother wind. Plus, the removable fan guard ensures you can easily clean the fan to avoid allergies caused by dust build-up. Low noise and portable: The high-quality pure copper motor effectively reduces noise caused by friction and provides a strong wind with less noise.