Small and robust - the Adventurer Opti features a patented optical water sensor that also serves as an integrated LED flashlight. The durable UV lamp provides pure drinking water for years with 8000 purifications. All portable SteriPen UV light water purifiers use germicidal ultraviolet (UV) light to destroy 99.9999% of all bacteria, 99.99% of all viruses, and 99.9% of all Giardia and Cryptosporidium. They purify 1.0 liters of water in 90 seconds or 0.5 liters in 48 seconds. With a UV lamp encased in a sturdy quartz protective shell, these water purifiers are environmentally friendly and designed for portability.