I love the air filter unit, but the 3 pocket filter that captures the 1 micron stuff fills fast (better than in my lungs I know) but it is expensive to replace. The electrostatic filter, if you need one, can be found elsewhere for 15 bucks and not $50 so shop around! My other complaint about the unit is that you have to do some rigging to make it hang from the joists but it can be done. Be careful not to bend up the box when doing so though!