P80-P100. Suitable for smooth and rough scratches and flat surfaces. This type of grinding wheel is usually used to treat the surface to use fillers. P100-P120. Suitable for removing scratches from coarser abrasives; P120-P180. Suitable for primer surface treatment; P180-P220. It is suitable for removing the top coat of automobile P220-P320. Very fine abrasive. It can be used manually without a sander. The challenge is to obtain an almost perfectly flat surface; P400-P800. Finally, the surface is treated before painting; it is suitable for wet grinding paint before painting;