Backpacker Editor's Choice 2011. Germicidal UV light destroys viruses, bacteria and protozoa. 8,000 treatments. Purifies 0.5 L (16 oz.) of water in 48 seconds or 1 L (32 oz.) in 90 seconds. Pocket size rugged purifier weighs only 3.6 oz. with 2 CR123 batteries (included!). Optical water sensor also serves as integrated LED flashlight.