GermGuardian FLT48252PKPC HEPA Genuine Replacement Filter B, Pack of 2This 2 pack of the GermGuardian HEPA replacement filter B is for use in the GermGuardian 3 in 1 HEPA air purifier system AC4825CA (Costco # 1165867). Its a combination filter that incorporates multiple layers of filtration including a pre filter charcoal filter and True HEPA filter to help improve indoor air quality. Features HEPA filter Captures 99. 7% of dust and allergens Stored in the back of the main unit Pre filter charcoal filter This layer