I smoke, drink coffee and pretty much seemingly do everything else that keeps teeth from being white, so this looked interesting. I've been using a brush on tooth whitening gel and that did make some difference. I'm starting out at maybe a 10 on their chart so I have plenty of room for improvement!It comes very nicely packaged with the mouth piece, three tubs of gel and some of the best short instructions ever. Twist the tub, apply the get, and turn on the mouthpiece. Put it in your mouth and wait 10 minutes. I've now done this 6 times over two weeks and I can certainly see a difference. I still have a way to go ( if ever ) to nice solid white teeth, but I have to say, it's working and any improvement is better than my current tooth coloring.The listing here says wear for 30 minutes but the instructions say 10 or 15 depending on blue light or blue and red light. No where can I find out the difference between blue and combo lights. Funny side note: when I go to rinse it off the water will actually turn the unit on. Also, this listing says to apply "drops" to the mouthpiece, but the instructions say to put the solution on your teeth. I have noticed a slight tingling from time to time, but it's subtle, nothing bad. I must have applied some to my gums ( and they do mention this in the instructions ). The mouthpiece fits well enough.Overall, it's working, it's super easy to use and while I'm not sure about using it daily ( I have no idea why ) I will continue to see the improvements. Those 3 tubes should last a long time.