20 In. x 25 In. x 1 In. Washable Electrostatic Filter Pad

MERV RATING: 7 Designed to Fit: True Blue RinseClean, Web Products, AirKontrol, American Air Filter, 3M, Whistle-Air, Precisionaire, Purolator, Allergy 4, and many other brands. Adjustable! Guaranteed To Fit Any Size, up to 20 In. x 25 In. x 1 In. Lasts up to 3 Years. The 3 Phase Progressive Density Filtration is designed to deliver optimal filtration with minimal burden on your home?s air handling system. In the initial phase, the white Pre-Filter traps larger sized airborne contaminants and allows smaller particles to pass through. This prevents the filter from filling up too fast and restricting the air flow. In the second phase, the light blue Mid-Filter is designed to mechanically trap contaminants that are one micron or less in size. This increases efficiency, providing better indoor air quality. In the final phase, the air becomes electrostatically charged and allows the filter to attract very small particles much the same way magnets attract metal.