Aprilaire replacement filters are interchangeable with the Space-Gard filters. These whole house air cleaners are made to tackle indoor air pollution. According to the EPA, our indoor air can be as much as 100 times more polluted than our outdoor air! With the greatest depth of all residential air cleaners at 6", you can be sure that there is plenty of available media surface to collect bothersome dust, impurities, and allergens. Available in two sizes - 16x28x6 and 20x25x6. Recommended use is 6-12 months per filter. Contact U.S. Home Filter today for help finding the correct Aprilaire replacement whole house air filter that's right for your home.