I bought a used 2016 Mustang that someone before me seems to have spent quite a bit of time on the freeway as there were a dozen chips in the bumper. (very small but noticeable as the car is white and the chips appear black). The grinding pen made it very easy to clean up all the wounds and prepare them well for painting without damaging the surrounding areas and making the touch-up more visible. Would definitely buy another one of these if I need to do more touch up work. Yes, the fibers are brittle and break easily. but that's the point. Take your time and don't use excessive force and this works very well even with very small chips.