True Blue 12"x24"x1" Fiberglass MERV Rating 2 30-Day Filter. Effective against pollen and dust/lint, it reduces dust and dirt buildup in air ducts, air conditioners, and furnaces. Made from heavy chipboard in a one-piece design, the EZ Flow II features continuous filament spun glass filter media that adheres directly to the frame without a retainer. UL Classified.