The simple, lightweight bagcomes to you with a filtered "straw" and pop style bottle top. All you have to do is fill the bag with water and screw on the top and drink. It couldn't get much easier. The filter removed the particles and makes the water safe to drink.
The whole package comes with a small ferro rod and striker which makes this a great deal on Amazon (sells for $19.99). Even if it sits in your go-bag for weeks, ready for your next hike, you will feel better knowing that it's there.