This is my second Alen product, and I am extremely pleased with both purchases. I own a Fit50, and one of the larger (1,100sq ft capacity) units, and I use the HEPA-silver filtres in both units. I am absolutely convinced that these units increase air quality substantially, as I have all but eliminated my dependence on allergy medications. When some painting was done recently (including oil-based primer), I was able to sleep in the room without suffering repercussions from the fumes; this has never before been the case. 

I would highly recommend these purifiers, and without reservation. As well, I have had occasion to contact the company for assistance, and I can confirm that the customer service is just as outstanding as the product. Thank you.