120-400 Generally suitable for removing the paint and smoothing, the surface is relatively rough 600-2000 Generally used for smooth surface fade scratches. 2000-3000 There must be no white scratches, the kind of snow white scratches, pay special attention to it! ! ! ! Because it can't be processed after 3000 3000-7000 Generally used for polishing but some things can only be smoothed 10000-20000 Generally used for from reflective surface to mirror surface.