Tier1 Replacement for Trane 21x23.5x5 Merv 11 BAYFTAH23M Air Filter 2 Pack Upgraded media rated at MERV 11 to capture 90% of particles, 1-3 microns in size Replacement for: Trane BAYFTAH23M and FLR06073 Up to twenty times more effective than ordinary fiberglass filters. This product is listed and rated by Underwriters Laboratories as U.L. Class 2