SteriPen Classic 3 Water Purifier with Pre-Filter Battery powered Ultraviolet light water purifier that is perfect for travel and outdoor use. Purifies up to 150 liters on one set of AA batteries Purifies a half liter of water in 48 seconds or 1 liter in 90 seconds. Simple and easy to operate. Device activates when the lamp is placed in water, simply insert and stir until the light shuts off. Destroys over 99.9% of bacteria Viruses and protozoa, like Giardia and Cryptosporidium Certified for purification by the water quality Association Fast safe effective and chemical-free doesn't alter Taste pH or other water properties reusable to purify up to 8,000 liters Tapered end fits most commercial water bottles, canteens, or drinking glasses.