20” Pleated Washable Water Filter Cartridge (1, 5 & 50 Micron)USAGE: Choose your micron rating from 1mic, 5mic or 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 20" filter housings. Prefilter for Rainwater Harvesting Systems, Well Water filter, Swimming pools, WVO Bio Diesel Filtering Pleated Cartridge can be washed down and reinserted into the housing to be used a number of times subject to water quality.