Whole house water filter systems are great solutions to help protect your pipes and appliances from sediment buildup and chlorine as well as scale - offering you great tasting drinking water from anywhere in the home. 3M Aqua- Pure Whole House Sanitary Quick Change Replacement Water Filter AP917HD-S is designed for the 3M Aqua-Pure AP904 Whole House Sanitary Quick Change Water Filter System. The AP917HD contains filter media that helps reduce sediment, chlorine taste and odor, and scale. It improves water quality and taste while supplying cleaner, clearer water to every water source point in the house. The scale inhibition feature uses polyphosphates in minute quantities to bind calcium and magnesium hardness minerals, preventing them from precipitating out and building up on metallic surfaces which can reduce flow rates throughout the home’s plumbing system. The innovative Sanitary Quick Change (SQC) design, an industry first for this application, allows for fast and easy cartridge change-outs without having to contact the filter media or the need for a filter wrench. Tested and verified by manufacturer's laboratory. Replace every 12 months, at 100,000 gallons of use, or sooner if a noticeable reduction in flow occurs.