The Katadyn TRK Gravidyn Microfilter is a free standing water filter that supplies up to six people with 6 months worth of drinking water before the frt cartridge change is required. The 0.2 micron pores in the filter elements trap all unwanted bacteria to produce good tasting safe drinking water. Just fill up the top with untreated water and let it drip through the three ceramic filter elements at 1 gallon per hour. The bottom compartment features a non-drip spigot so you can easily fill your glass or bottle with drinking water. And it all comes with 2 year warranty. It's a great way to always have drinking water handy at your cabin, garden house, base camp or caravan.