Very well whitens teeth. Also against the background of tanning (I'm pale creepy), generally amazing. I keep 15 minutes, for the first time I kept 30, and increased sensitivity, plus blood went, but, it's probably myself inaccurate, I probably decided to hold it. About 2 weeks, maybe with something, used daily, literally for 5 applications already saw a good result. Now I use it in a day. Gel is enough for a long time, if you do not apply with a smear, as I did for the first time (half the syrin...