This handheld water purifier uses ultraviolet light to destroy viruses, bacteria, and protozoa in 0.5L (16oz) of water in 48 seconds or 1L (32oz) in 90 seconds. The SteriPEN Classic weighs 5.7 oz. with 4 AA lithium batteries (not included). Single push button activates UV lamp capable of 8,000 treatments. Tapered end mates with canteens. Neoprene case with belt loop included.