Backpacker Magazine 2011 Editor's Choice Award winner, the Adventurer Opti UV water purifier from SteriPen is essential gear for adventurers around the world featuring a revolutionary optical eye to sense the water. This patented technology provides safe use and the standard insulating sleeve around the UV lamp allows purification in even the coldest of waters. Similar to other SteriPEN models, the Opti purifies 0.5 L 16 oz. in 48 seconds and 1.0L 32 oz. in just 90 seconds. Adventurer Opti's optical sensor doubles as a convenient LED flashlight. It's a great backup light when camping or taking a night time walk to refill your water bottle.