Katadyn Pocket Filter – LifeTime Guarantee. The most economical, durable mini-water filter on the market today. The ceramic filter element can process up to 13,000 gallons of water before needing to be replaced. With proper care the Pocket Filter should last for years. It is very compact ( about the size of a 2 – D cell flashlilght), easy to operate & clean, and transforms turbid, biologically contaminated water into safe drinking water.