the very edges round the sides etc, these bits can be damaged easy, go real light and fast over these bits, also watch the swage lines - the bits that are like folds down the lenght of the car in the middle of the doors, where the metal has that fold, these bits are also pressure points when using rotarys, i do above this fold first, 4" pad fits perfect between rubber of window and the swage line and i then do below the line after, and a quick light pass over the swage line between but dont put too much pressure on these bits, hope that makes sense