They haven't been used yet, but it's important to have items like this in our toolbox if we plan to install ADA (ie Braille and Embossed) signs for schools. Very often we are surprised that the surface we have been told is one thing and there is something else below the surface, or we find an electrical control of where our sign is and moving the sign means a sudden installation on the Tile, maybe, and not stucco. That's why it's so important to have a kit like this available to our sign installers. To be honest, if you're lucky, they're of little use and therefore last a long time, although they're probably not professional if you have to use them all the time. For our use, mainly in emergencies, they are exactly what we need and at a good price.