SteriPEN Aqua provides value-priced UV water treatment with the same effective technology which kills viruses, bacteria, and protozoa. Perfect for occasional travel and home emergency kits, lasts for up to 3,000 liters of water purification. Operates on four AA batteries. Purifies 50 liters of water on one set of alkaline batteries or supercharge you Aqua with lithium batteries and youâ€™ll treat about 150 liters! Easy-to-use. Just press button, place in water, and stir!