4 Years Supply (24 pcs) for 3 Stage Whole House Filtration System or Reverse Osmosis RO. Replacement Set of 3 filters: Sediment, GAC, CTO Carbon Block Universal Reverse Osmosis RO Replacement Set of 3 filters: Sediment (8 pcs), GAC (8 pcs), CTO Carbon Block (8 pcs). Fit 3 – Stage Whole House Systems. Fit regular 10″ x2.5″ housing. 10″ Sediment Filter, 5 Micron. Removes dirt, silt, sand, rust, and scale particles. 10″ GAC Granulated Activated Carbon Filter. Removes chlorine, chloramine, VOCs and etc. 10″ CTO Carbon Block Filter. Removes chlorine, chloramine, VOCs, bad taste, and odor. High quality guaranteed.