Great kit for those In need of some serious teeth whitening. After I took off my braces, my teeth were naturally yellow and had spots, so even though my teeth were straight, it was still embarrassing to smile. So, I purchased a box of crest 3D strips. They're on the pricey side but the results last for quite a while. My teeth stay white for about 8-9 months before I actually need to rewhiten my teeth. BUT, be careful not to over use the whitening strips. At one point, my teeth became very sensitive to hot and cold foods/drinks.