Review on 🌀 Fiberglass Furnace Air Filter - Flanders Precisionaire 12X20X1 by Shawn Bass

I thought smart. I decided to install a small second gas heat pump to supply gas to our house and heat the basement. I had no idea 12x20x1 filters would be required, much less how difficult they are to find. I take it back. You'll find 12x20x1 in those with metal frames. They whistle so loud my little pup thinks someone is whistling for him so he flies down the steps then gets up and looks at me and says "that's not funny man." This is a simpler and cheaper version but they work fine. I change about every 30-45 days. They don't whistle and are quite strong.