20” Jumbo String Wound Water Filter Cartridge (1–100 Micron)USAGE Choose your micron rating from 1mic or 5mic. (lower the micron the lower the sediment size removed, if using multiple stages, start with a higher micron down to a lower micron) Fits all 20" Jumbo filter housings. Used as stage 1 in sediment water filtering. Hard Well Water filtering DESCRIPTION 20" JUMBO String Wound Sediment Water Filter Cartridge (For Removal of sediment, dirt, rust, particles). Used as a first filtration stage. 20" JUMBO