The scale inhibition feature in the AP904 whole house filtration system uses polyphosphates in minute quantities to bind calcium and magnesium hardness minerals, preventing them from becoming a solid and building up on metallic surfaces, which can reduce flow rates throughout the home's plumbing system. The stainless steel head assembly with 1 in inlet and outlet connections helps provide high flow rates of up to 20 gallons per minute (gpm) / 75.7 liters per minute (lpm) to meet the needs of most residential applications. Our innovative sanitary quick change (SQC) design allows for fast and easy cartridge change-outs without having to contact the filter media or the need for a filter wrench.