The SteriPen Traveler is a water purification system that purifies your water in seconds with the technology of ultra-violet light. It eliminates dangerous bacteria and viruses without the hassles of boiling water. The SteriPEN traveler is capable of purifying 200 half-liter servings of water on just one set of AA lithium batteries. It’s designed to fit perfectly into commercial water bottles, forming a seal that lets you keep the water in the original bottle for purification. Just insert the Traveler securely into the mouth of the bottle, turn it upside down, and you have safe drinking water in less than a minute.