The Steripen uses Ultaviolet light to deliver water purification. The Classic 3 offers great ergonomics and batterly life. It features an 8,000 treatment lamp to deliver a lifetime of purification. Uses 4 AA alkaline batteries to purify up to 50 liters of water, or 4 lithium batteries to purify up to 150 liters. Includes a neoprene storage pouch. Batteries not included.