I have been using the crest white strips for a few months now and my teeth look beautiful. I always get compliments from strangers at least once a day about how beautiful my smile is and how incredibly white my teeth are. I always tell them it is from my crest white strpis. I promote this product so much becuase it truly works. My dentist asked me what bleaching trays I used and he was amazed when i told him it was the crest strips. He was amazed and couldn't beleive my results. I use the strips once a day not twice because they do cause me sensitivity but when I use them once a day I don't feel the sensitivity. I will use a strip every once in awhile in the mornings to keep up my results. This is the best teeth whitening product I have ever tried and no one should be skeptical to try it. I love this product and reccomend it to anybody who had a problem with the shade of their teeth. It is very affordable depending on which package you buy and I always wait for the great coupons to come out before I buy them. My last doctor visit, I was talking and my doctor interrupted me to ask me how I got my teeth so white. When I told him he said he was heading to the store right after work to buy some. I beleive in this product more than anything. Thanks for such a great product.