Nordic Pure 20x25x5 Air Bear Replacement MERV 12 Pleated Plus Carbon air filters measure an actual depth of 4 7/8”. This is a fraction of an inch larger than the traditional measurement, so always be sure to measure the actual size of your filter’s housing, as your system could also use this size. Air Bear Replacement MERV 12 Pleated Plus Carbon air filters are made of a new dual material where the MERV rated material and carbon material are pleated together to form a formidable obstacle to dust and odors. Because the carbon is also pleated, there is 3 times as much odor-fighting capability in each filter. Each time air passes through a Nordic Pure pleated furnace filter, lint, household dust, pollen, dust mites, pet dander, smog, mold spores and germs from coughing or sneezing are removed. MERV 12 air filters are comparable to air filters with the MPR rating of 1500-1900, a FPR rating between Red and Blue, and an APR rating between Platinum and Diamond. Particles in indoor air are measured in microns; for scale, a human hair is about 70 microns wide. Each Nordic Pure 5” MERV 12 air filter will capture more than 90% of 3.0-10.0 micron contaminants and up to 90% 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 and work. We recommend that you change your air filter every 30-90 days to maintain maximum efficiency and indoor air quality.