Sorry about the poor pics. It's kind of hard to get in there to get a good one. I have one fan at each end of the tank, and they blow across the end of the bulb near the endcaps and circulate the air out the back of the canopy. I didn't keep the packaging, but I think they rated at around 22 decibles. They're really quite and put out pretty good air flow. (I think it was something like 27 cfm, if that's the correct unit.) One of the best parts about these, though, is that they come with a "quick disconnect." That is, I made a connection to a 12 volt DC plug, but the other end is not connected to the fan. It has a small connector instead. The fan has a small cord with the other connector. So, you just put the two connectors together and bingo. (I know that sounds confusing, but I don't know all the technical terms for these electronic components!) What I like is I can disconnect the fans if I want without worrying about unplugging everything. Oh! I lied. The BEST part is they were only like $5 a piece!