SteriPen Classic Handheld Water Purifier Destroys viruses, bacteria and protozoa--including Giardia and Cryptosporidium--using ultraviolet (UV) light Takes 48 seconds to purify 16 ounces of fluid, 90 seconds for 32 ounces Easy to use--just press a button to start and the SteriPEN shuts off when purification is complete No pumping, no chemicals, no test strips, no timekeeping, no lubricating, and no replacement filters required Powered by 4 AA batteries; weighs 8 ounces and measures 7.6 inches long