Nordic Pure’s 16x25x3 MERV 12 Air Bear Cub Replacement Plus Carbon air filter is meant to replace the air condition filter for any system that requires a 3” depth. Unlike other A/C filters where the nominal and actual sizes differ by a fraction of an inch, the Air Bear Cub Replacement Plus Carbon has a nominal and actual depth of 3 inches exactly. Keep that measurement in mind when you are measuring your furnace air filter. Nordic Pure 3” MERV 12 Trion Air Bear Cub Replacement Plus Carbon filters are made of a dual material where the MERV rated material has been fused together with a carbon layer. Odorous gases and vapors (VOC) are attracted to and held by the activated carbon material while maintaining excellent air flow properties. All Nordic Pure pleated HVAC filters are manufactured using a heavy duty, moisture resistant beverage board frame. The frame has 2 strips of foam tape on 2 sides. There is a metal mesh support grid bonded to the pleats for extra support. MERV 12 Air Bear Cub Replacement Plus Carbon furnace air conditioner filters are comparable to HVAC filters with the rating of MPR 1500-1900. We recommend that you change your AC air filter every 3 to 6 months, depending on your home or office environment to maintain maximum efficiency and economy. This will help keep your air conditioning and heating systems running efficiently, saving money on utilities and costly maintenance.