10” PP Sediment Water Filter Cartridge (1–100 Micron)USAGE Choose your micron rating from 1mic, 5mic, 10mic, 20mic, 50mic (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 10" filter housings. 5mic used as stage 1 in most reverse osmosis systems. 1mic used as some stage 2's on reverse osmosis systems prior to the carbon block. Used as first stage in well water, KOI, Aquarium and almost all other water filtering