Review on 💨 Easycargo 2-Pack 40mm USB Mini Fan: Quiet and Portable Cooling with Multi-Speed Control (45x45x23mm) by Jennifer Vargas

I use these two fans to cool a small hybrid (tube/solid state) headphone amp. Each fan only produces about 6 cubic feet per minute, which doesn't give much air movement. No problem. I simply fold them in half (mind the direction of airflow) and stack them at a 45 degree angle. With a dual fan set, like a small "chimney", the fans can move about 12 cubic feet per minute, which is enough to cool my headphone amp's small vents. A speed controller is also a good option, but I've found that I have to run the fans at full speed to get the cooling I need. The fans make some noise, but that's to be expected. However, it's not too loud. Ideally if you have a room you should use much larger fans running at much lower speeds to keep the fan quiet, but for smaller devices with limited space you may not have that option. In these cases, dual installation of these two small fans for cooling works well. UPDATE 7/26/19. My rating has been downgraded from 5 to 2 stars due to poor quality control. Ordered a second pair of these fans in July and the controller didn't work right out of the box. It's possible to plug fans directly into the USB port to spin them at full speed, but the quality control of the controllers seems suspect. Another July review also had the same issue with the controller not working. It would be very easy to check before they leave the factory door. I guess the company that makes them doesn't care.