LotFancy 20x25x1 Air Filters, 6 Pack, MERV 11 Pleated HVAC AC Furnace Filters - Walmart.com
Amazon.com: BestAir A201-SGM-BOX-11R AC Furnace Air Filter, 20" x 25" x 6", MERV 11, with Cardboard Frame, Fits 100%, For Aprilaire/SpaceGard 2200, 2250 (201) & Lennox PMAC-20C 24", Pack of 2 :
Kirkland Signature 2200 High Performance Furnace Filters, 4-pack | Costco