The original handheld UV water purifier is now even better. With SteriPEN Classic 3, one set of four alkaline batteries will treat 50 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 simple to use: remove the lamp cover, press the activation button, submerge in water and stir. In 45 seconds you have a half liter of safe drinking water or purify a full liter in 90 seconds.