I bought these on sale and with a coupon - super cheap, and I'm sort of glad I did because the results were rather lackluster. My teeth aren't too yellow, but I have a few problem spots, and i dont feel it really did much for them.Overall, I really cant tell the difference! It doesn't come with a whitening chart like Crest Whitestripes do, so you dont really have much to compare your before and after with.The stripes are quite thick, but thats just a comment - not a pro nor a con, personally. On the plus side, I did not experience any tooth sensitivity or pain while using these.I probably wont buy these again, the results just were not satisfactory for the price.