I got this about two weeks ago and was very impressed with the build quality and the sleekness, it makes my tank look nice. These look very well built and it has helped me keep my tank from over heating. I am very happy with them though they did cost me a pretty penny $$$.
I have them hooked up to my Ranco controller, they basically turn on when it gets over 79. I now have a very stable tank temp. Before, I was getting way too much fluctuation and as a result, my fish got ick.
The neat thing about these fans is that they are built from some kind of metal/aluminum material and they are salt creep resistant. So, you wont get any corrosion and they will not break down in a year like my CPU fans always did from salt creep. They are also individually replaceable, I forgot what company sold the fans only. They are called Titan fans.
Anyhow, here is a pic. They have clips that grab onto the tank and can be angled for better evaporation (cooling).