Nordic Pure 20x25x5 (4-3/8 Actual Depth) Lennox X6675 Replacement MERV 14 Plus Carbon AC Furnace Air Filter, Box of 2, 2 Piece

I replaced my Lennox filter with this brand. My furnace started making a high pitched noise and the sheet metal would make a banging noise at the end of the heat cycle. Long story short, this filter restricts air flow so bad it causes a vacuum underneath it, sucking in the sheet metal housing and severely overworking the system. Caveat emptor

I have been using Nordic Pure carbon filters instead of the original Lennox filters for my furnace. They appear to work just as well as the Lennox filters but they are half the cost. I would recommend them to anyone looking for a more affordable furnace filter.

thanks