SteriPEN is the world's leading manufacturer of ultraviolet, handheld water purification systems. SteriPEN is fast, lightweight, easy, and effective. SteriPEN comes in a variety of models for travel, outdoor recreation, family heath, and emergency preparedness situations, making safe drinking water available to anyone, anytime, anywhere, at a small fraction of the cost of bottled water. Cities around the world have been using ultraviolet light (UV) to make water safe to drink for over 100 years. UV light destroys germs' ability to reproduce and make you sick. It destroys 99.9999% of bacteria, 99.99% of viruses, and 99.9% of protozoa. SteriPEN is the original handheld UV water purifier Keeping outdoor enthusiasts healthy with ultraviolet light for over 12 years. Hundreds of thousands are in use from mountain ranges, to tropical beaches, exotic cities to home emergency kits. Most models are reusable for up to 8,000 liters - that's over 7 years of safe drinking water! Specifications: Weight 5.5 oz / Opti - 3.6 oz Dimensions 7.6 x 1.5 x 1.5 in / Opti - 6.1 x 1.5 x 1 in Lamp Life 8,000 treatments Battery AA Lithium (Not included with purchase) / Opti - CR123 or RCR123 (included with purchase) Battery Life Lithium Disposable: 200 treatments (16oz./0.5L), NiMH: 200 treatments (16oz./0.5L); Alkaline & NiCd not recommended / Opti - Disposable - 100 treatments (16oz./0.5L) Rechargeable - 50-60 treatments (16oz./0.5L) Minimium Bottle Diameter 20mm (0.8 inches) / Opti - 35mm (1.4 inches) Filter Compatability Tapered End (PreFilter and FitsAll) / Opti Non-Tapered End (FitsAll Only)