I wanted a unit that would remove air particles in the house, as my wige has bad allergies. I was looking at the Sharper Image unit but when I found Calutech's whole house unit that was cheaper than Sharper Image's unit that did only one room, I was excited. I purchased one and am very happy with the unit. I hdave had no problems with it and any questions about it have been quickly answered fully by email. A good company to do business with and I highly recommend them!