When designing our new shop filter system the only size I could find in the big box store was one-inch. Thankfully Filterbuy has options from which I can more efficiently complete the project. Now to test the effectiveness.
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.