Hunter is the leader in this field. I have had one in my bed room for years now and I don't know of a better one. The come in sizes to fit the room. A small one will clean the air in a room 8 x12, medium 10x14 and the large which I like will cover a room 15 x 20 with ease. Don't be fooled by the high dollar machines, they will not do any better job than hunter will do.