The replacement ceramic element is suitable for the classic water filter Katadyn Pocket. The silver-impregnated ceramic filter element effectively combats bacteria and protozoa. The mini-pores of the filter ceramic (pore size: 0.2 microns = 0.0002 mm) are smaller than the microorganisms. Due to their size, these cannot pass through the filter element and are thus removed from the water. The filter element should be replaced after a maximum of 50,000 liters. The capacity of the ceramic filter element depends on the water quality. The dirtier the water, the more often the ceramic needs to be cleaned. Cleaning is also possible on the go, but it reduces the filter capacity from the maximum of 50,000 liters. If the opening of the testing template fits over the ceramic, the ceramic filter element needs to be replaced.