I have tried three products: (1) professional whitening gel obtained from my dentist, which worked well, but was expensive and made my teeth very sensitive; (2) Crest White strips, which I found to be just okay for the price; and (3) Plus White 5 Minute Bleach Whitening gel. I really like the last one. It is very economical, selling for around $6-8 each. However, I use it with the professional teeth molds made by my dentist, not the generic rubber one that comes with the kit. I don't think it would work very well with the mold that comes with it and there would be a lot of waste. I have found this product in Walmart, Target and some grocery stores.