These DO work, however they made my teeth sensitive as ever! I can only use them once per month or so, as frequent usage made my teeth literally hurt. I'm not sure if this is a common occurrence but I don't like that. The wraps are easy to apply and instructions are easy to understand. They made my teeth whiter as well, which is the point. For a person with less sensitive teeth, this may be the perfect whitening product as the price is right!