Listing is for 3 filters.The Watts SF5-20 is a compatible replacement filter that fits the following water filter housings:Housings which require standard sized 20 inch water filters (20 inches x 2 1/2 inches)The Watts SF5-20 Compatible String Wound Filter is a 5 micron water filter cartridge made of FDA grade polypropylene fibers that will reduce sediment, sand, dirt, rust, and other impurities in your water. This Watts water filter (SF5-20) offers excellent chemical compatibility and high dirt holding capacity, all at an economical price. This string wound filter is made of FDA grade polypropylene and is suitable for potable water as well as industrial use.The Watts SF5-20 polypropylene string wound filter is also commonly known as a PP filter cartridge.Watts SF5-20 String Filter Cartridge:5 Micron RatingMax Temp: 140 FDimensions: 20 inches x 2 1/2 inches Reduces: Sediment, Sand, Dirt, RustMedia: FDA Grade Wound Polypropylene (PP) FibersFilter life depends on water quality and usage. This Watts filter should be changed when a decrease in pressure is noticed.R1R2S1