I have it mounted in the back of a wood cabinet, so I can't actually measure it anymore. But it's just a standard 2U rack mount panel with 3 80mm fans added to it. Standard rack mount spacing is 19" wide, and the 2U size means it should/will be 3 1/2" tall.
As for the noise, my guess is that at about 5 feet away and out in the open, that it's probably about 25-35db. They claim it's 28.5db, but they don't say at what distance either. And depending upon how and where it's actually mounted in a cabinet or a rack, then it can probably be even a bit less noise than that, because putting it in something like the back of a cabinet it will muffle it some. Also if you turn 1 or 2 of them off, then the noise will go down even more. But it is after all, 3 80mm computer type fans, so it will never be totally silent.