Steripen Classic 3 UV Water Purifier is their most versitile model. It is also the winer of Time Magazine's Best Invention of 2001, if offers enhanced ergonomics and battery life as well as improved water resistance. An 8000 treatment lamp delivers a lifetime of purification. Cleans clear water and tap water.  Note! Batteries are not included. Treatment size: 0.5 or 1 liter Tretment time: 48 or 90 seconds Lamp life: 8000 activations Batterytype: 4 AA batteries lithium or rechargable NiMH Effective against: bacteria, protozoa, cysts, virus 1 click for 0.5 L, 2 clicks for 1 L Weight 178 g Dimensions Length: 7.3 cm Width: 1.7 cm Height: 1.7 cm