What a terrific air filtration system! The FLEX scrubs the air in our bedroom. Running it for a couple of hours before turning in, we can smell the difference in the air, which was certainly no longer true of our previous HEPA device. And the FLEX is much quieter, generating a soothing background at setting #2 that (as silly as this may sound) reminds me of the ambient noise of Star Trek's USS Enterprise. It was there, but you hardly noticed...