Excellent in that these are really quiet. USB powered and very well made. I now have 4 of these operating to cool down my hifi rack where I have valve power amps running. Even when playing soft music at low levels, I do not hear the 4 fans operating at maximum speed - these come with three speed settings, unless I made an effort to watch out for them. Great value and highly recommended if you are looking to cool your hifi gears especially if you are using valve or tube amps and similar components.

Bought this to help cool my aging Xbox 360; just until the Series X comes out anyway. The Xbox was freezing after about an hour of gaming. Despite a deep cleaning in January it's HOT to the touch. The addition of these fans has increased the heat dissipation and playtime without any noise pollution. I'll be back to buy the larger component coolers once the current ones I have on my expensive equipment items give up the ghost.

DISH Network recently replaced our DVR with the 722 Duo model. Some online research told us it's a model plagued with problems that all seem to originate with the box overheating. We figured we'd be proactive, and looked into cooling fans; a little research led us to these AC Infinity fans, and we're glad we got them. We placed one on each side of the DVR vent holes - right side draws air in, left side blows it out. Since setting these fans up a couple weeks ago, our DVR isn't even warm to the touch. Even on the highest speed, you cannot hear them run - they just sit there and quietly do their job. Should we need more of this type fan in the future for other equipment, we will definitely be return customers. Very happy with our purchase!