Using similar UV treatment techniques found in water bottling plants and hospitals, the feather-light SteriPEN Adventurer destroys 99.99 of bacteria, viruses, Giardia, and other nasty little bugs. Heres how it works: Dip the SteriPEN Adventurer in any vessel containing up to 16oz of clear water. When the sensor detects water, the germicidal UV lamp comes on and administers a 38-48 second dose, and thats itpurified, Montezuma-free water for your drinking and cooking pleasure. The Adventurer comes in a protective hard case for rugged trips and handles the occasional tumble or crush like a champ. Includes two non-rechargeable lithium CR123A batteries.