Nordic Pure MERV 7 Plus Carbon air filters are made of a dual material where the MERV rated material has been fused together with a carbon layer. It will help eliminate unwanted odors as well as trap most airborne dust and particulate matter for fresh, clean air. 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 air filters are manufactured using a heavy duty, moisture resistant beverage board frame. There is a metal mesh support grid bonded to the pleats for extra support. Our air filters use permanently electrostatically charged material that acts like a magnet to help dust cling to the air filter. MERV 7 Plus Carbon air filters are comparable to air filters with the rating of MPR 600. We recommend that you change your air filter every 30-90 days to maintain maximum efficiency and economy. Important Note: Almost ALL furnace filters have a different "actual size" than the nominal size printed on the air conditioner filter. It's best if you measure your air filter for the EXACT size and compare it to our "Actual Size" - and then you can be sure your A/C air filter fits!