I have them only a few days. They were placed on a Dell 15.6. Perfectly. Their adhesive seems very strong (and so far with daily use inside and outside in a backpack). The package also includes 2 small pieces of adhesive surface that you can cut and place on the "feet" so they don't slip. Personally, I didn't do it. It doesn't bother me. It doesn't slip as you type. The angle is very comfortable. Even after many hours of use. I will come back later for reevaluation.