CP3 12 Pack Economy Harsh Environment Pre Filter for Air Purifiers 7.25" x 7.25" Fits FreshAir 2, Surround, Everest and others by CP3;

Your air purifier gets really dusty inside from small dust, smoke, pollen, and other contaminants. Using one of our paper-thin, harsh environment pre filters allows you to keep the inside cleaner, avoid extra cleaning and keeps your warranty intact because the inside is kept cleaner. These filters fit on the back of your existing filter just under the back plastic grid that holds the filters in place. They capture airborne particles, keep the internal parts cleaner, reduce your monthly maintenance, help prevent a misuse warranty condition and more. Replace each month when you clean your unit.