The SteriPEN Classic 3 with 40-micron pre-filter is the latest, most versatile model in SteriPEN's award winning Classic line. Winner of Time Magazine's Best Invention of 2001, it offers enhanced ergonomics and battery life as well as improved water resistance. An 8,000 treatment lamp delivers a lifetime of purification. Use four AA alkaline batteries to purify 50 liters of water or four lithium batteries to purify 150 liters. Includes a neoprene storage pouch. Batteries not included. Features: - Purifies water using UV light - Weight: 6oz - Runs on 4 AA batteries (not included) - Volume options: 1 click = 0.5 liter, 2 clicks = 1 liter - Effective against microorganisms - Suitable for small groups up to 3 people - Suitable for cloudy water - For daily or very frequent use - Lightweight and portable for on-the-go adventures - Includes storage pouch