mine was a Honeywell with a charcoal HEPA filter like this one:
http://www.amazon.com/gp/product/B00...ENX6TRVMSWBRWS
I was surprised how well it worked, you could smoke in a room and a couple minutes later no one could tell. I ended up giving it to someone that smoked in their small apartment with three kids that had asthma, felt bad for her kids.