The vacuum brazed diamond drum wheels are designed for making an inside circle, oval, or arc. The tool features the fastest material removal rate of any grinding drum when used on granite, marble, concrete and engineered stone. 30/40 grit diamond (coarse) for grinding hard granite. 70/80 grit diamond(medium) for grinding medium/soft granite and marble. 5/8-11 thread fits most grinders, 2" x 2" and 3" x 2" are available.