Elegant design, the external air flow valve is very practical. I placed it (the valve) at the end of the hose coming out of the tank so I have easy access. It is very powerful and of course, most importantly, silent. It is truly silent (!!) and I haven't even placed it under the cabinet yet (where I intend to) until I receive the check valve. It is on the lid, which theoretically is not as stable as the cabinet shelf and wobbles more easily since it's plastic.
I am very happy because the noise issue was stressing me out after one or two failed choices and since I often sleep in the room where I have the aquarium.
Perfect, I hope it lasts.

Honest air pump for the money. It is quite powerful. At full, it mixes everything up! Fortunately, it comes with an air flow regulator (external). It has one output but with a splitter you will have a second air output. For small/medium aquariums it is more than enough, maybe even excessive. And yes, it is quite silent. Compared to my old mouse type that used to drive the world crazy. It does not include a non-return valve so you have to purchase it separately.