Nordic Pure’s 16x25x3 MERV 8 Air Bear Cub Replacement filter is meant to replace the filter for any system that requires a 3” depth. Unlike other filters where the nominal and actual sizes differ by a fraction of an inch, the Air Bear Cub Replacement has a nominal and actual depth of 3 inches exactly. Keep that measurement in mind when you are measuring your filter’s housing to determine what filter is best for you. Nordic Pure 3” MERV 8 Air Bear Cub Replacement filters are made of electrostatically charged synthetic materials that attract and capture most airborne particulates in your home. Each time air passes through a Nordic Pure pleated furnace filter, lint, household dust, pollen, dust mites, mold spores and other contaminants are removed. MERV 8 air filters are comparable to air filters with the MPR rating of 600-800, FPR rating of Green, or APR rating of Gold. Particles in indoor air are measured in microns; for scale, a human hair is about 70 microns wide. Each Nordic Pure 3” MERV 8 filter captures up to 85% of airborne particles as small as 3.0-10.0 microns. The effective life of your air filter depends on both the inside and outside conditions in which you live. We recommend that you change your air filter every 3-6 months to maintain maximum efficiency and economy.