Review (5/5): These work much better than I thought they would.!
For the price and ease of use, these can't be beat. I used a 20 day box about two months ago and was very happy with the results. A little sensitivity but it went away. I just started another box and am again feeling a little, tiny bit of sensitivity, but nothing even very noticeable. I'd compare these to professional results and I am a smoker so that says something (although my teeth weren't very bad before, now they're great!)