Excellent product . Easy to set up . Purchased 2 units for my home . Definitely makes a noticeable difference in the air we breathe. For quite a while I had been smelling exhaust fumes all over the house, this with no furnace on...no explainable reason...we couldn't understand where it might be coming from. I was diagnosed with emphysema in January, so my husband took a leap of faith and purchased this unit...and another smaller one for our bedroom. After only 1 day I noticed a considerable difference...(It's auto setting went into turbo drive when I noticed the exhaust on the first day we used it...confirming that I wasn't imagining the odor), and now there has been NO exhaust fumes in a week...Just set it on auto & let it do its thing. Definitely would recommend this Alen product .