Review on Portable 4 Inch Mini USB Desk Fan: Quiet, Strong Airflow & 40° Adjustable Tilt Angle - Perfect for Desktop Office (Black) by Ronnie Toups

For a small diameter fan this little bug moves the air well in all three settings. As for the "quiet" part of the description, each person who bought this item has their own definition of "quiet". I'm expecting a noise from the fan blades. I don't think there is a reliable way to get rid of the sound of the blades pushing the air. When working, there is almost no noise from the blades, but this does not disturb the silence. A low hum can be heard regardless of the type of surface on which the device is placed during operation. I'm pretty sure it's coming from the engine. Suggestion: Don't put this on a stand or some kind of box; the hum gets louder. On the bright side of the hum, it merges with my noise generator and renders it inaudible. There is no battery, it is USB connection and yes! Plugging a USB into an outlet makes it run just as easily as plugging it into a computer port. Portability is a bit inconvenient as it doesn't fold in half; but he survived the night ride in a small suitcase. So far a solid device and I'm considering buying another one. Just because I have one, I can leave it at home while the other travels around the countryside with me.