Sterilize your water without boiling? With the SteriPEN Adventurer Opti UV Water Purifying Pen, you simply stick the pen into your water bottle, stir and it shines germicidal ultraviolet light into the water to kill the bacteria, viruses and protozoa that could very well make you sick. It takes about 90 seconds to sterilize one liter (32 ounces). A couple of heads-up: you’ll want to make sure you have rechargeable batteries and you’re using a water bottle with a 1.75 in. diameter opening so you can fit the pen in there. Kind of amazing, and by the way, it can work as a backup flashlight too.