AquaPure AP817-2 by 3M Purification Replacement Carbon Water Filter Cartridge. Replaces AquaPure AP-815-2. Dimensions: 20 1/8” L x 4 5/8” W. 25 Micron Nominal Filtration Flow Rate: 20 gpm Dirt and Rust Reduction. Rigid Construction Withstands Stressful Conditions. Maximum operating temperature of 100° F. Made from FDA (CFR 21) Compliant Materials. Chlorine, Taste/Odor Reduction. Polyethylene Outer Shell, PolyKLEAN Center Core. Granular Activated Carbon. The AP817-2 is widely regarded as the most sensible choice in the niche of water filter replacement cartridges. It has proven expertise in removing particulate, rust, and the unpleasant taste & odor of chlorine from drinking water. It has a polyethylene outer shell and a polyKLEAN centre core -- these two attributes combine to provide a very durable composition along with amazing filtration capabilities. The filter uses granular activated carbon. The AP817-2 captures sediments on its rigid, polyethylene outer shell. It has an impressive 40,000-gallon capacity at 10 gpm, ensuring there is no dearth of clean drinking water in your home. The filter uses a radial flow design that allows for finer activated carbon action and helps to maintain the most minimal pressure drop. The double open-ended design fits all large-diameter housings.