Great!
I went with this (14day classic) set over the premium (7-10day) set because of the milder peroxide strength and boy am I glad I did.  Even with the classic set, I was getting sensitive teeth (especially the tops of the bits of the molars that get covered by the strips).  As a result, instead of using the strips twice a day like you are supposed to, I only use one set of strips a day (so it will take 28days for me).  So far so good - my teeth appreciate the once-a-day regimen and my teeth have been noticeably whiter even after the 3rd day.  I do wish the strips for the lower teeth were wider.  Highly recommended!
Rating: 5 stars