This teeth whitening kit is only available through dentists.
Although it costs more, it is a far better, safer product than ones you can buy over the counter.
An impression is taken of your teeth, and then they make up a set of plastic "teeth" from this, and these fit very tightly over your teeth. The bleaching agent goes inside and you can pick which teeth you want to whiten.
I paid $330 for 10 vials at my local dentist, and this is more than enough for whitening -I have enough to do it once more, and for me it took about 10 days, twice a day.
Summary Even though it seemed slow, this is a great product which I would highly recommend.