40#~240# The coarse grit series is used for sanding hard, coarse and rough things, such as metal, wood, walls, etc. 240#~600# Commonly used for secondary sanding, some less demanding ones can be sanded directly into shape. 600#~1500# Fine sanding range, for mahogany furniture, amber, linden seeds, jade, etc. 1500# and above Fine grinding and polishing can be used to polish objects with high quality requirements.