True Blue 18x18x1" Fiberglass MERV Rating 2, 30-Day Filter. This filter effectively traps pollen, dust, and lint, reducing dust and dirt buildup in air ducts, air conditioners, and furnaces. Made from heavy chipboard in a one-piece design, the EZ Flow II filter features continuous filament spun glass filtering media that adheres directly to the frame, eliminating the need for a retainer.