First of all, it takes too much effort just to put everything in place. I don't know what you call those black button things but I'm just gonna call them buttons and it took me a lot of effort just to put those buttons in place along with the filter.
Secondly, when I did finally manage to put everything together and try to use it, it feels like as if I'm trying to breath in a vacuum chamber.
Lastly, upon putting everything in place, the filter's alignment is a little bit off.
I can handle 2 and 3 but not 1 and 1 is the main reason why I gave this product a 1 star.