XPOWER AP-1500D Air Purification System HEPA-300-406PV Stage 4 V-Shaped HEPA FilterXPOWER Stage 4 HEPA Filter for XPOWER AP 1500D Filter Air Purification System Compatible with the XPOWER AP 1500D Portable HEPA Air Filtration Systems, this 11. 5 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 the long life of this filter. Replace as needed when the indicator light illuminates and