I read many other reviews about the Crest White strips and really wanted to try myself. I got the Professional Effects kit because I really wanted to know if they really worked. It was quite pricey for a drugstore product since it was around $50-60 with tax. I am almost done the box (2 strips left). It’s like putting tape on your teeth and then pulling it out afterwards. It is easy to use but the sensation afterwards doesn’t feel good. After 3 days straight of use, I felt sensitivity from my teeth and gums. There was minor swelling from the gums and my teeth would suddenly hurt for 3 seconds then stop. It is a strange feeling. So I stopped using it for a few days before restarting. I’ve been afraid to use the strips continuously so I would use them for 2 days and rest for a few days to avoid sensitivity. I think it did light my teeth a little bit but the results are pretty negligible. For all the uncomfortableness I will not repurchase this again.