Was not too effective at whitening my teeth

I was really excited to try this product because of the great reviews it had but was not pleased with the results. I do have discoloration on my teeth because I had braces for awhile so I decided to try this product and it managed to whiten my teeth a little bit but the results only lasted for 15-30 minutes. I did not see a great difference in my teeth after I finished using the product. This product is also an expensive product but more affordable than the very high end whitening products that I have seen on the market. Overall I was not too pleased with this.