I purchased the FLEX air purifier on a recommendation of a friend who uses Alen air filters for her pet allergies. I have noticed that her Alen air purifiers really do work when I am at her house. This summer I went in search of an air purifier due to extreme wildfire smoke in my house. Although I had to wait a bit longer for the Alen air purifier due to demand, I am glad that I did. The FLEX is fabulous! It is compact, well-designed, light-weight (absolutely no trouble moving it) and really does the job. It makes a difference. I plan to try it out this winter to clear the air from my woodstove. I wish I had purchased this years ago!