[wbc409]

It is special glue, and if done right the button on the windshield that the mirror mounts to is almost impossible to remove without damaging the windshield. When I worked on squad cars we attached those same metal buttons to the windshield for video cameras. If we mounted the button wrong, we glued another tab on top of the old one or next to it. We never tried to remove the mounts from the windshields.