This is the best teeth-whitening system in the market right now. I've tried the liquids, toothpastes, trays, gels, lights, you name it but none have whitened my teeth like the Supreme Professional Crest Whitestrips. This is the second time I've used the system this year for maintenance purposes. They are so easy and convenient to use. The strips actually stick to my teeth and remove easily. When I first used the strips, I saw a shade lighter two days later. By the time I completed the 42 strips (the box comes with 84, 1 lower and 1 upper strip per application), my teeth were bright and white. I started receiving compliments and I noticed the difference in photos. I was actually very surprised and happy with the results. I used two strips in the morning and two in the evening for 30 minutes each time as recommended. Time-permitting I did two consecutive treatments. What I also love about these strips is that my gums were not sensitive to the peroxide. If you want whiter teeth in a relatively short period of time, these are the strips to use. I absolutely love them.