The 12x18x1 MERV 7 Plus Carbon air filter is a convenient pleated air conditioner and furnace filter that has been impregnated with activated carbon. It will help eliminate unwanted odors as well as trap most air borne dust and particulate matter in your home or office. With each pass through the filter, the air in your living environment improves. Our high efficiency activated carbon filter helps eliminate smoke, pet smells, garbage cans, bathroom odors, litter boxes and cooking. Odorous gases and vapors (VOC) are attracted to and held by the activated carbon material. The MERV 7 electrostatic filter helps trap airborne particles including pollen, household dust, mold spores, and dust mites. The Nordic Pure anti-microbial media will not permit the growth of bacteria or mold resulting in a healthier environment. It can be installed in practically any HVAC system without modifications. MERV 7 Plus Carbon air filters are comparable to air filters with the MPR rating of 500-600 or FPR rating of Green. The effectiveness of your air filter will depend on your environment. We recommend that you change the air filter every 30 to 90 days depending on the conditions inside and outside of your home.