Works really well!
I’m always a bit skeptical about teeth whitening products as many I’ve used in the past haven’t work and have been a complete waste of money. This however works, really well. I used it twice a day for about 4 weeks (until it was finished) and after the first few days I noticed a difference, by the time I’d finished the pen my teeth were noticeably whiter. So much so that I’ve ordered another one. Easy to use and effective. Worth the money.