The Germ Guardian FLT4010 Replacement Filter is designed to replace the filter in your AC4010 Air Purifier. It is an air cleansing system that has one combination replaceable filter which combines several filtering technologies to capture up to 99% of dust and allergens, kill germs, and remove odors. It's suggested that the filter be replaced every 6-8 months, depending on use, to maintain optimum results. Germ Guardian's FLT4010 Replacement Filter uses several layers of filters. The Pre-Filter captures large dust particles, lint and pet hair. The True HEPA Filter captures 99% of airborne particles such as dust mites, debris, mold spores, pollens and pet dander. The Photocatalyst and Charcoal Filter uses the UV-C light to activate the Titanium Dioxide that decomposes odor caused by smoking, cooking and pets. It also prevents the growth of bacteria, germs and mold.