Katadyn Pocket is slightly misleading in its name. This is not an ultra compact pocket filter, but rather a sturdy workhorse of a purifier, with excellent durability. Its materials are chosen so as to give a long service life and it will serve groups of 1-4 people in size. - The filter has a 20 year guarantee - Silver impregnated, ceramic 0.2 micron filter element that filters bacteria and protozoa - Filtering speed approx. 1 l/min. The ceramic filter's capacity is approx. 50.000 l, depending on water quality - As part of the manufacturer's Endurance series the Pocket is designed and built for demanding conditions, and is able to handle very turbid water Don't allow your filter to freeze. Water expands as it freezes and may break the filter element. *Note!* A water filter or purifier tablets cannot remove the toxins created by algae bloom, and therefore do not make water containing said toxins safe to drink.