The Filterbuy replacement air filter 17x21x1 (actual measurements: 17 x 21 x 1) ensures that your furnace, air conditioner, 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 1000 - 1200 & FPR 7) is recommended if you have pets or allergies due to its capability to trap 95% of airborne particles, protecting your home or business from smoke, smog, debris, lint, pollen, mold, dander, and other forms of dust without impacting air flow. The high-quality construction features an electrostatically charged, pleated design that captures more harmful particles and prolongs the products lifespan by three times that of fiberglass models. 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. 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. Filterbuy: Breathe Freely!