Actual Filter Size: 19-3/4 x 24-3/4 x 3/4 inches. 2 filters included (Up to a 6 month supply). Each filter lasts up to 90 days. Foremost in air filtration. Helps eliminate odors with the power of baking soda. Reduces contaminants that may cause allergies. Minimizes strain on HVAC equipment. Durable moisture-resistant frame. Merv 8 Ashrae rating. 52.-2-2007. Up to 90 days effective protection against these common household contaminants. Pollen. Dust. Dust mite debris. Pet dander. Mold. Bacteria. Virus carriers. Odor. What is Merv? Merv (Minimum Efficiency Reporting Value) is a rating system developed by the American Society of Heating, Refrigerating and Air Conditioning Engineers to give a simplistic method of comparing filters. The higher the merv rating, the more efficient the filter is at capturing smaller particles. Replacement: When to Change Your Filter: It is important that most indoor air filters be changed as recommended on the packaging to ensure the best possible air quality for your home and family. Certain instances such as high traffic areas, pets or smokers in residence, or other situations may require more frequent changes. All graphics are for representational purposes only. Does not imply actual performance. Classified UL listed: Air filter unit as to flammability only 542L. flandersfilters.com.