Review on Coolerguys Dual USB Fan, High Cooling Capacity, 50Mm, High-Performance Efficiency, Dimension: [1.97 X 0.79 X 1.97 Inches], 5V, Ultra Quiet Cooling Blower Fan by Kyle Hoes

I purchased two of these for use in my home theater center. I have a surround sound receiver and PC which fit into the main shelves in my TV stand which is closed in the back apart from a hole for cord/wires and is open on the front. These devices, especially my receiver, were running extremely hot. And the power source fan and motherboard heat sync fan in my PC were running constantly and becoming quite loud.I put a set of these fans in each shelf with my receiver and computer. Since everything is set up to my liking and I don't have a lot of slack on my speaker wire, I decided against permanently attaching the fans in the back of the shelf, as this would have required taking everything out and reorganizing. Instead, for each device, I placed one fan blowing in (parallel to the back of the shelf) and one blowing out to the front on the opposite side (perpendicular to the back of the shelf, flush with the side). This essentially created a wind tunnel which pulls cool air in on one side of the device, across the back of the device(mixes with hot air), and then blows the hot air out the other side.Everything is running SOOOOOOOO much cooler. The fans are very quiet, and even with four running, there only a slight hum if I mute the audio.I only wish the cords were a bit longer to accommodate my receiver (USB only on the front)and that there were wire screens on BOTH sides of the fan.But other than that I have NO problems with these fans. And for the price, it is definitely worth protecting your expensive equipment from damage due to overheating or in the case of a computer, reduced performance.