I saw an interesting way to purify a large volume of air on an episode of ASK THIS OLD HOUSE. They used four of these filters taped together as a square box with the air flow facing in.Then they mounted a 22" square 3 speed fan on the top drawing the air through the filters and out the top. Sealing off the open bottom of this arrangement allowed a large volume of air to pass through the filters removing dust and germs. I purchased these filters to build and test this system to try and eliminate dust from our pellet furnace. So far it seems to be working great.
Aside from the 5 emails I've received asking to review my purchase, I'm very happy with my value and quality of the filters I received. I saved so much money from not buying in a store!