The AFB Gold MERV 11 furnace / air filter is recommended for home or business owners that have pets as it is specifically designed to filter particles as tiny as one micron, including pet dander, lint & dust, dust mite debris, pollen and mold spores, auto emissions & smoke. While not quite hospital grade like our AFB Platinum (which we recommend for asthma and allergy sufferers) our AFB Gold is a premium quality product that is an upgrade from the AFB Silver and significantly more effective than a standard fiberglass filter. Whenever you are choosing an air filter, make sure that you compare the nominal and actual size of the furnace filter that you are replacing. In this case, the 'nominal' size of the filter is 17x25x1 while the 'actual' size of the filter is 16.5 x 24.5. Generally, the nominal size is rounded and in bigger print while the actual size is in smaller print and in parenthesis to the side. The AFB Gold MERV 11 filter is designed to last 3 months, or 3 times the average fiberglass filter. The filters ship directly from the manufacturer to your doorstep, allowing AFB the ability to offer a premium product at a reasonable price. Each quantity purchased is for a pack of 4 filters. Note that AFB filters come in AFB Bronze (Merv 6), AFB Silver (Merv 8), AFB Gold (Merv 11), and AFB Platinum (Merv 13). The most commonly used filter for home or business use is the AFB Silver (Merv 8). If you have pets or allergies we recommend the AFB Gold (Merv 11). If you have asthma or other respiratory illness, we recommend the AFB Platinum (Merv 13). AirFilterBuy: Breathe Better!