XPOWER Stage 3 HEPA Filter for AP-2500D Filter Air Purifier SystemStage 3 HEPA Filter for XPOWER AP 2500D Filter Air Purifier System Compatible with the XPOWER AP 2500D Portable HEPA Air Filtration Systems, this 12 inch. thick Professional HEPA Filter captures contaminants such as bacteria, allergens, mold and even 0. 3 sized sub micron particles at a rate of 99. 97%. Several pre filter Air Scrubber stages ensure a long life of this filter. Replace as needed when indicator light illuminates and other filters have