This is a GENUINE GermGuardian Filter.  It is important to only use genuine Guardian Technologies replacement parts to maintain product performance and warranty.  All parts that are not genuine will void the warranty.  Only one single combination filter needs to be replaced every 6-8 months depending on the use of the product.</br>GENUINE Replacement filter for GermGuardian Air Purifier Models AC4010 & AC4020 and Black+Decker BXAP040</br>Multiple levels of cleaning include HEPA, Pre-Filter and a Charcoal layer to help improve indoor air quality</br>True HEPA Filter captures 99.97% of dust and allergens as small as .3 microns such as household dust, pet dander, mold spores and plant pollens.</br>Charcoal filter reduces common odors from pets, smoking and cooking.</br></br>Product Description</br></br>GermGuardian FLT4010 True HEPA GENUINE Replacement Filter A is a combination filter. It incorporates multiple layers of filtration including True HEPA, charcoal and PCO to help improve your indoor air quality. True HEPA filter captures 99.97% of airborne particles as small as .3 microns. It is recommeded to use with with GermGuardian AC4010, AC4020 and Black+Decker Model BXAP040. The use of this genuine Guardian Technologies replacement part will maintain the product's performance and warranty.</br><br/>http://www.amazon.com/gp/product/B003AKNK4A