The Wet Diamond Drum Wheels a set usually comes with grit #50,#100,#200,#400,#800,#1500,#3000,(Coarse to Fine, 1 piece each grit size ) Material : diamond and resin/ Aluninum Designed for wet polishing with water feeding holes User manual: Use them from coarse to fine, the final polishing. The whole process takes water to cool fully, but in the polishing stage,water should not be too much