I got these thinking that it would be cool to have a refillable tank, I happen to read it wrong. It is actually for when you smoke a cigarette it catches the “goo” out of the cigarette. The part that truly is the worst for you, it strains out. I don’t know how else to explain it. It would be good for people that was to clean up the chemicals/tar coming from the cigarette. Just like my teacher in middle school did, he smoked a cigarette through it, and it showed how much is being inhaled into your lungs. It is pretty cool, but I can’t say that I would use them much.