I purchased two of these fans to use on a horizontally mounted radiator in a HAF X case.
I was smart to do a test run before installing them in the case because there is a problem. The fans are very quite when mounted in a vertical plane. Unfortunately, these fans are very noisy when mounted in a horizontal plane.
Both fans make a noticeable rubbing sound when mounted in horizontal plane. This is not uncommon, depending on the bearing and design, but it should be stated in the specifications. It is also possible that I received two fans with problems.
This would make a nice case fan but not if you plan to use anti-vibration material between the case and the fan. The fan does not have four straight edges. Thus, you will only have contact pressure near the four corners. You would have to cut your own material for a good seal.
This is a good fan. I am giving it 2-stars to draw attention to a potential problem for some builders.