Review on Amerlery Picture Invisible Hardwall Mounting by Charles Lewellen

I think this product will work well on some concrete and brick walls but certainly not all. I tried using these books in the concrete basement of my house and they failed miserably. After four attempts, each time with a new hook, I ended up with a crumbly, pockmarked, salable wall, and the metal tips on the hooks often curled inward, presumably because they couldn't break through the wall. Pre-drilling might work, but just hitting the hook with a hammer won't work.