I admit, I was very skeptical. I live in an older rental house that needs the duct work cleaned badly. I also have pets. I read the reviews and figured what did I have to lose other than a bit more money? I am impressed. My congestion, in the mornings and on days when I’m home, is now noticeably less to non-existent. These filters are game changers. I’ll gladly spend a bit more money for something that works. Plus, as an added bonus, they are made here in the U.S.A.