The Filterbuy replacement air filter 20x24x4 (actual size: 19.38" x 23.38" x 3.63") ensures that your furnace, air conditioner, heat pump, or HVAC system is circulating the cleanest air possible to help preserve your budget and healthy lifestyle. MERV 11 synthetic media (comparable with Micro Allergen Defense MPR 1200 & FPR 7) is recommended if you have pets or allergies with its capability to trap 95% of dust particles while protecting your home or business from smoke, smog, lint, pollen, mold, dander, and other forms of debris without impacting air flow. High quality construction features an electrostatically charged design with 8 pleats per foot that captures more harmful particles and prolongs the products lifespan by three times that of fiberglass models (replace every 90 days for best results). Plus, our industrial grade beverage board frames are paired with dual wire backings that significantly outperform traditional cardboard compositions by improving structural integrity with their ability to endure temperatures up to 200 degrees Fahrenheit and withstand exposure to moisture. Installation is also made simple with the addition of easy-to-understand arrows that help identify the direction of air flow and subsequently the way the filter needs to be placed. To top it off, all our components are 100% manufactured within the United States and designed with recyclable materials, providing an eco-friendly alternative to enhancing your air quality.