I should have saved my money! I have sensitive teeth and it was so painful that I couldn't even make it through the treatment! I think I did 2 of the 3 (or 4) 20 minute sessions. Also, some of the gel got on my gums and burnt the crap out of me!! I did Zoom prior to getting my veneers, but it was like a package thing. However, it didn't cross my mind that I wouldn't be able to use my take home tray after I got the veneers because my teeth were not the same. Despite all of this, my teeth did lighten 2 shades. If I didn't have such sensitive teeth and was burned by the gel then I'm I would of have better results. But overall this was a waste of MY money. Good luck!