I was in a time crunch and got a coupon from lifebooker. They said I would see 2 – 8 shades lighter. I didn’t really see a difference after the session. Parking in this location was such a pain. I do have a few white spots on my teeth from acidic drinks, those became whiter… wasn’t really the effect I wanted. Probably won’t have this again. I’m better off with crest white strips.