AP917HD 3M Aqua-Pure Whole House Water Filter ReplacementWe manufacture the 3M Aqua Pure Whole House Sanitary Quick Change Replacement Water Filter Cartridge AP917HD for the AP93 system as an activated carbon filter with a nominal heavy duty particulate reduction rating of 5 microns and a 1, gallon capacity. This cartridge design is suitable for use on both chlorinated (municipal) and non chlorinated (well water) systems. Replacement cartridge provides up to 100,000 gallon capacity, approximately one year