Katadyn Guide Backcountry Camping Water Filters remove particles, cysts and parasites 0, 3 microns or larger, The Katadyn Guide camping filter element is glass-fiber with over 143 square"" of filtering surface area, A carbon prefilter prevents larger particles from reaching main filter extending its life, Chemicals and odors are adsorbed through the activated carbon core producing better tasting drinking water, Katadyn Guide Replacement Camping Filter Includes: replacement filter, o-ring and silicon lubricant, Filter Element is 9, 5"" x 2"", SKU: CWD690