With the SteriPEN Classic 3, one set of four alkaline batteries will treat 100 half-litres or 50 full litres of water. Or supercharge your SteriPEN with a set of lithium batteries and you’ll treat up to 150 litres! The Classic 3’s enhanced LED indicator panel lets you know treatment size and status of batteries and UV lamp. The Classic 3 is sleek and ergonomic with an easy-to-remove twist-off lamp cover. Like all SteriPEN UV water purifiers, the Classic 3 is simple to use: remove the lamp cover, press the activation button, submerge in water and stir. In 48 seconds you have ½ litre 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 chemicals that can leave an unpleasant aftertaste.