When camping, hiking, backpacking or traveling the Classic 3 with Pre-Filter is the perfect pack to keep you safely hydrated. Classic 3's UV light destroys over 99.9% of waterborne microorganisms that cause illness.With SteriPEN Classic 3, one set of four alkaline batteries will treat 100 half-liters or 50 full liters of water. Or supercharge your SteriPEN with a set of lithium batteries and you'll treat up to 150 liters! Classic 3's enhanced LED indicator panel lets you know treatment size and status of batteries and UV lamp. Classic 3 is sleek and ergonomic with an easy-to-remove twist-off lamp cover. Like all SteriPEN UV water purifiers, Classic 3 is simple to use: remove the lamp cover, press the activation button, submerge in water and stir. In 48 seconds you have A 1/2 liter of safe drinking water or purify a full liter in 90 seconds. Compared to standard chemical treatments that can take up to four hours, that's safe water fast without adding chemic...