Bests & Worsts Reviews from Amazon

I wish I'd done more research re: CFM and CADR. This is a small device purifying air at the excruciatingly slow rate of 20 cfm. This may be sufficient for light duty in a VERY SMALL room (closet) but do your own math first. (For my purpose of removing pipesmoke from a well ventilated ~165sf room, I need a minimum of 220 cfm!) I also noted the pic of the filter shows pre-filter, HEPA and 'charcoal' layer as three separate layers with the charcoal layer having a somewhat honeycomb design. In fact, there's only a black pre-filter over the HEPA. Perhaps the pre-filter is imbedded in charcoal, but I doubt it. Hope this helps