Tier1 Replacement for Ultravation 20x25x5 Merv 13 AC Furnace Air Filter 2 Pack Upgraded media rated at MERV 13 to capture 90% of particles, 1 microns or smaller in size 98% efficient filter media that captures small dust particles before they can collect on your coils This product is listed and rated by Underwriters Laboratories as U.L. Class 2 This product is listed and rated by Underwriters Laboratories as U.L. Class 2