4 Pack USB Brushless Cooling Fan 40mm High Performance DC 5V Speed 4200 RPM for Small Appliances Series Replacement For Desktop

A great little fan for keeping your systems cool and not overheating. Just plugs into a USB port on your system, and it powers up when the system turns on (I'm using on a PS3). Slight noise from such a small thing, but it's nothing too overly annoying. Definitely a worth buy.

I use this with a mini Linux-based computer (about 4"x4"x1/2". I used a very small piece of double-sided tape to attach it to the hottest section of the computer. I did not cover any computer cooling fins. The fan immediately brought down the temperature and continued to do so all day and night. It does make some noise, but it is no big deal. And if the fan ever gives out, I have three more as backups!

All I needed were small fans that ran off of USB in order to add a cooling option to the inside of a costume. These were exactly what I was looking for, so I'm happy. They have a very quiet buzz that only really affects me because the fans will be close my face, but it's not too bad of a sound so I'm not really bothered. They also aren't very powerful, but I wasn't expecting much out of a tiny 5V fan, and it works well enough at close range. I also noticed some other reviews saying that there were some exposed wires on the units, but it seems they are a bit more contained on the ones I got so I am not too worried about that. Overall, pretty satisfied.

im using this little fan for a desktop green house, It does wonderfully to circulate air. i wasnt sure if the moisture or humidity would be a problem but havent come across anything yet. while I have a very limited idea of what this is original for but i dont think its this lmfao. it does make a noticeable amount of noise if i dont have my headphones on its not annoying or high-pitched.

Yet another Cinderella story where the "shoe" fit perfectly. Purchased these cooling fans to insert into air vent on a bat habitat to draw out the hot air to try to keep temperatures below 100 degrees. Time will tell.

I got these little fans because currently my computer tower only has a single exhaust in the back, but it has a grate on the bottom front of the case, but no real way other than negative pressure to pull the air into it. So I figured I could get these, wire them up, and set them to a switch so they could just pull the cooler air into the bottom of the case. It would circulate through and be pushed out by my exhaust fan. And while they do do that, and it does work well and helps to cool my computer tower, they are very loud. Loud enough that when I stream, I'm unable to really use them because my microphone will pick them up more so than it even picks up my air conditioner. That is only 20 feet away from me. So while they work, and they are fairly powerful for their size, they are by no means quiet.

I wanted some small, USB powered fans for a project of mine. These are perfect and do exactly what I need them to do. Plus, the price was great. If you need some small fans, these might be just what you're looking for.

These 40mm USB brushless cooling fans work initially and move a decent amount of air for their size. They’re easy to power via USB and fine for light-duty use at the beginning. Unfortunately, durability is a major issue. Out of the four fans, three failed within about 90 days or less. That makes them unreliable for any setup where long-term operation matters. For the price, you do get basic functionality, but lifespan is disappointing. Overall, okay for short-term or temporary projects, but I would not rely on them for continuous use.