Tier1 Replacement for Carrier 19x20x4-1/4 Merv 13 FILCCFNC0021 Air Filter 2 Pack Upgraded media rated at MERV 13 to capture 90% of particles, 1 microns or smaller 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