Tier1 Replacement for Lennox 16x25x3 Merv 11 X0581 Air Filter 3 Pack Upgraded media rated at MERV 11 to capture 90% of particles, 1-3 microns in size. Replacement for: Lennox X0581 and X5427. 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