Review on 🔍 Nordic Pure MERV 12 Honeywell/Lennox Replacement AC Furnace Air Filters - 20x20x5 - 2 Pack by Corby Muin

One filter was not 3/16" square and was not flat, the other just wasn't flat. By "not flat" I mean the waves on the cardboard. Surfaces on both sides that would prevent them from laying flat on the filter holder. This means that some air flows around the filter. It was easier to just use foam tape to get a good seal than to return them. What's really weird is that my other order from Nordic was perfect for different size filters. All three blocks were flat and accurate. So if you're shopping from Nordic, don't buy 4 inch filters as they were probably made in a drunken sailors line. (2 inch filters were ideal.)