Tier1 Replacement for American Standard 21x26x5 Merv 13 Air Filter 2 Pack Upgraded media rated at MERV 13 to capture 90% of particles, 1 microns or smaller in size Replacement for: American Standard BAYFTAH26M, FLR06074 and Honeywell TRN2621T1 Up to twenty times more effective than ordinary fiberglass filters. This product is listed and rated by Underwriters Laboratories as U.L. Class 2