Review (2/5): Whitens O.K., but messy and difficult to use.
Product seems to whiten O.K., but the problem lies in the difficulty of use. The instructions say to brush the gel on your teeth with a toothbrush, and then put in your tooth trays; or, to apply a tiny amount to each "tooth" in the trays.
I thought the toothbrush method would waste too much, so I attempted to apply to my tooth trays. That turned out to be nearly impossible. I have used DayWhite in the past, and that product comes with tiny nozzles that are used to dispense a small amount into each tooth section. The Watts Power has no nozzle, or any way to dispense just a small amount. The gel comes out of the syringe in a big blob, with no way whatsoever to control the amount. I just have to spread it along the tray as best I can, but it is extremely messy, and some teeth end up with a lot, and some with just a little. The gel is also very thin, and once the trays are on your teeth, much of the gel oozes out. I constantly have to blot my gums.
If the maker would supply a nozzle of some kind, or some way to control the amount dispensed, this might be a decent product. But I am sure I will get nowhere near the amount of applications indicated, since so much of the gel is wasted, no matter which method of application is used. Seriously doubt that I will order this product again.