Amazing!  It works and my teeth are not sensitive!
This product is amazing!  After using it for one evening (you do 4 cycles each time you use it) I could see a substantial difference.  My teeth look as white as they did years ago.  I am a coffee drinker and enjoy fruit such as cherries... both of which can stain your teeth significantly.  My teeth are not at all sensitive from this product.<br />Make sure you use the protective lip care before each treatment cycle.  You have to use it on your lips and inside your lips.  I think it is because of the gel you apply to your teeth.  I didn't get it on the inside for a cycle and the inside of my lip was a bit sensitive for a few hours.  But I also have extremely sensitive skin.  It felt fine later that day.<br />As far as the fit of the "universal" tray.  For me, it's not a great fit, but I think that is because I had 4 adult teeth pulled when I was a kid (my mouth was too small and my orthodontist had not started using palatal expanders).  So I need to hold the tray in with one hand... which is a bit tedious, but totally worth it.<br />I will definitely continue using this product.
Rating: 5 stars