This replacement set contains 1 year supply of the following filter cartridges: * Stage 1 - NSF Polypropylene sediment pre-filter to extract suspended materials such as sediment, silt, rust, insects, and other particles down to 5 micron. - 2 pieces * Stage 2 (multi-stage) - KDF-85 removes heavy metals, iron and hydrogen sulfide. It also controls scale and microorganisms such as bacteria and algae. Catalytic Carbon and Granular Activated Carbon (GAC) remove chloramine, chlorine and its byproducts such as THM and TCE, unpleasant taste and odor, hydrogen sulfide (rotten egg) smell, PFAS such as PFOS and PFOA. - 2 pieces * Stage 3 - 5 micron NSF High purity coconut shell activated carbon block filters reduces compounds that contribute to bad taste and odor and creates sweeter tasting water.