SteriPEN® handheld UV water purifiers are effective, fast, light and easy. Designed by Hydro-Photon Inc. for providing safe drinking anywhere, SteriPEN ultraviolet light purifiers disinfect 16 ounces of water in 48 seconds or 32 oz. (1 L) in 90 seconds. Ultraviolet light is a proven purifier used in city water plants and by bottlers throughout the USA. Recipient of the Water Quality Association's Gold Seal, SteriPEN is backed by extensive lab testing, and its effectiveness exceeds the US EPA Microbiological Water Purifier Standard. SteriPEN models weigh 3.6 oz. to 5.7 oz with batteries.