Lightweight water purification for peak performance in the outdoors! SteriPEN Adventurer Opti was built for the toughest mountains and rivers in the world. Stylish, pocket-sized and rugged – the multi-award winning Adventurer Opti incorporates Steripen's patented optical water sensor that also serves as an integrated LED flashlight. An 8,000-treatment lamp delivers a lifetime of purification. Includes two long-life CR123 lithium batteries and a neoprene storage pouch. 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.