I have never been a real outdoors person, but I do know that water is the most important thing to have. The problem is, you can’t just drink water from any source. If you were unfortunate enough not to bring your own water, your problems are solved. The SteriPen is a way to sterilize water to make sure it is safe for drinking. Within minutes, you can have water that is safe to drink. Using the SteriPen, you can kill viruses, bacteria and protozoa. It works on 4 AA batteries and weighs 3.5 ounces. This makes it perfect for backpacking and travel.