Teeth Whitening Gel : Subtle Difference

I received this product for free for testing purposes. I tried this product by using it twice a day on a dry toothbrush combined with the whitening toothpaste I use everyday. I timed myself for two minutes each use and made sure to brush as long as recommended. The taste didn't overpower my tooth paste and the gel was easy to use. I repeated this use for 7 days. On day 3 or 4 my teeth were a bit sensitive directly after brushing for a few minutes. Definitely not the harshest whitening system I have used, but it did make my teeth a bit sensitive. My before and after pictures did show a slight but noticeable difference. Definitely would not consider my teeth "whitened", but they are a bit whiter and shinier.