I used these for a particular problem. I had a 1/2 (with bumps on it) concrete wall in my basement. Everything I tried to stick to the wall didn't stick. Things like "stick wood" wouldn't work because of the bumps. This worked perfectly.  It is a sponge like material so it deals well with the bumps and sticks like you wouldn't believe. The only thing I don't like is that it is very hard to cut vertically. It is also crazy expensive so you can't make mistakes.  I also discovered that because of the sponge like backing if I made an error and stuck some on top of the other... all I needed to do was pound it with a hammer and it seemed like a natural continuation as the sponge material would be flattned.