MERV RATING: 11 - FPR "Filter Performance Rating": 6 - Specifically designed for families with allergies and pets. 53 times more effective than fiberglass filters and will last up to 4 months. During the manufacturing process, we charge the filter media with an electric current. This process allows the filter to attract very small particles much the same way magnets attract metal. The end result is a far more effective filter. The Electrostatically Charged filter media filters sub-micron airborne allergens like dust, dirt, pollen, pet dander, dust mite debris, microscopic allergens, smoke and smog. 100% Synthetic filter media will not support the growth of Bacteria, Mold, or Fungi in normal use.