The Pocket is a classic water filter by Katadyn. It is extremely high quality and robust which lets it withstand the most extreme conditions. This water filter was the first portable one of its kind and to this day is still the best. It is constantly being further developed and is now even easier and better to use. Its mechanism is tried and tested: a ceramic filter with micro pores (pore size approx. 0.0002 millimeters) reliably removes bacteria, protozoa etc. As the filter is easy to clean you will not need any replacement filters and the lifespan is an approximate 50,000 liters ? enough for several people for a long time. There is a 20 year warranty, as Katadyn only uses the highest quality materials. On a long trekking tour, on an expedition or anywhere else ? the Katadyn Pocket works reliably and will always provide the best drinking water.