The SteriPen Adventurer Opti offers the ultimate in fast, convenient water purification. Compact and lightweight (103g including batteries) the SteriPen Opti is easy to pack and ensures youll always have access to safe drinking water. SteriPen creates ultraviolet light that disrupts the DNA of microbes in seconds. Without functional DNA, microbes cant reproduce or make you sick. Simply press the button to activate, place in clear water and stir until light turns green (48 seconds for 0.5L/90 seconds for 1L). Effective against bacteria, protozoa and viruses.