When camping, backpacking & hiking, if you won't have access to the power grid for several days a time, this is the water purification system for you. SteriPEN Adventurer Opti was built for the toughest mountains and rivers in the world.When camping, backpacking & hiking, if you won't have access to the power grid for several days a time, this is the water purification system for you. The Adventurer Opti UV water purifier is essential gear for thousands of adventurers and features a patent-pending technology - an optical eye senses water to ensure safe use and effective treatments. The revolutionary optical water sensor doubles as an integrated LED flashlight for added convenience on the trail or around the campsite: hold down the activation button for three seconds to illuminate the darkness.Rugged design and construction trusted by thousands of endurance athletes. Adventurer Opti is powered by two CR123 batteries making it a lightweight water purification system ...