Nordic Pure’s 16x25x3 MERV 10 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 10 Air Bear Cub Replacement filters are made of electrostatically charged synthetic materials that attract and capture most airborne particulates in your home or office. Each time air passes through a Nordic Pure pleated furnace filter, dust, pollen, dust mites, pet dander, baking flour, mold spores and germs from coughing or sneezing are removed. MERV 10 air filters are comparable to filters with the MPR rating of 800-1000, FPR rating between Green and Red, and APR rating between Gold and Platinum. Particles in indoor air are measured in microns, which are 1/1000 of a millimeter (a human hair is about 70 microns wide). Each Nordic Pure 3” MERV 10 air filter will capture more than 85% of 3.0-10.0 micron contaminants and up to 65% of 1.0-3.0 micron contaminants. 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 indoor air quality.