Product review (4 stars): Works Best with Gorilla Glue
Mine came off after about  3 weeks, even though I was very careful too install exactly per the instructions :-(  The bottom of my granite has some kind of mesh on it, which I couldn't scrape off before applying the brackets, maybe that was the problem?  After the brackets came off, I used Gorilla Glue as others have advised to stick them back on, and it has lasted for over a year now with no signs of loosening.