Tier1 Replacement for American Standard 21x26x5 Merv 11 Air Filter 2 Pack Upgraded media rated at MERV 11 to capture 90% of particles, 1-3 microns 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