Useful
It works exactly as you'd expect it to. Blow smoke in, get deodorized 'clean' air out. Good for avoiding bothering other people with your smoke, also good for avoiding attention from your parents, RAs, probation officer, employer, cops, the NSA, etc. Pro tip: when it becomes difficult to blow into, put it in the microwave for about 3-5 seconds, take it out, and firmly blow into it. You will feel the filter losing the water that's clogging it and you might see some water vapor come out the end. It won't be like new, but it will give a little extra life to the filter before it needs replacing (you can use this trick multiple times, but it's less effective each time, and you risk melting part of it like I did).
Rating: 5 stars