The Katadyn Steripen Aqua UV water purifier ensures that you will always have safe drinking water close. Compared to other water purification systems this products works with an UV light (UV-C). In total the UV light is suited for 3.000 applications. The UV-light fights off the micro-organisms in the water to make sure you don't get sick. This Steripen destroys 99.9% of viruses, bacteria and protozoa. Perfect for every outdoor enthusiast, traveller and backpacker. The Steripen Aqua works with four AA batteries. The batteries are not included.