A few days ago I used Klear's action Teeth whitening System. I didn't get a whiter teeth (maybe because initially I had the whitest color from the scale that they provide). The only result after applying the product ... FRONT TEETH CRACKS AND CHIP the same evening:((( Be careful if you want to save your smile. Even not so white (like in the magazines), your teeth are not for a single day. Don't "kill" them with this product!!