In just 48 seconds, your water is safe to drink. Now you're free to hike and travel wherever you want, without the need to carry or store your own water. SteriPEN is proven to be safe and effective, eliminating over 99.9% of bacteria, viruses and protozoa that cause water-borne illness. SteriPEN has earned the Water Quality Association's Gold Seal, certifying its effectiveness. SteriPEN Ultra is the most advanced UV water purifier around. The OLED display clearly indicates treatment and battery status. With an internal rechargeable battery, there's no need to carry spare batteries. When fully charged, Ultra will treat 100 half-liters or 50 full-liters of water and its UV lamp will last for 8,000 treatments.