I have tested this product for nearly two weeks, between 30 and 45 minutes per day with the gel, gutters and the lamp (which to regularly change the 2 button batteries after 4-5 hours of use). And strictly no results! And therefore produces TOTALLY INEFFECTIVE IN MY CASE !!! Initially before treatment had my teeth whiteness "normal": I do not smoke, do not drink alcohol, coffee etc ... After treatment, I even feel that the teeth have yellowed ...! Conclusion: I highly recommend tooth whitening kit PRO WHITE