Really Happy
I've used a handful of teeth whiteners but this was the first pen for me.  Wow!  No kidding, in just 4 days of use my teeth are so noticeably whiter.  I am so surprised because I truly did not expect anything to work like you see on tv commercials.  But take my word for it, and I will truly buy it again, in fact, it came with a paper to give you one free pen if you come to the amazon site and do a review...however, they don't say to give a good review!  After you do your review, you just copy it and email it to them and they send you a free pen...I hope this turns out to be true.
Rating: 5 stars