|I bought 2 of these and 2 extra filters. They seem to be good construction. The first thing you should do is fill it with water and WITHOUT THE TUBE INSTALLED and let it leak into a sink for about 1/2 an hour. I learned that with the first one. The filters like any other carbon filter let some charcoal dust through at first. You don't want that in your tube; practically impossible to get the stuff out. The downside to these is that you have to suck REALLY HARD to get any water out. I still give it 4 stars though because it is so simple and quick to get water from sources you don't know to be safe. As a previous reviewer stated, when it is in your pack or vest - you feel the filter.
I recommend this product, but don't buy it unless you have an idea what you're getting into. It is a survival item not a bladder you fill at the closest sink for a hike.|