Tier1 Replacement for Carrier 19x20x4-1/4 Merv 8 AC Furnace Air Filter 2 Pack Rated at MERV 8 to capture particles 3-10 microns in size Replacement for: Bryant FILBBFNC0021 and Carrier FILCCFNC0021 Original box type design This product is listed and rated by Underwriters Laboratories as U.L. Class 2