4" Dry Diamond Polishing Pad, Grit #50 X 2 Pads Free 1-3 days expedited shipping by USPS Grit #50 for coarse initial polishing or filing down the surface Recommend 2500 rpm or less to avoid melting resin and color transfer Light weight, high concentration of diamonds to polish very fast and aggressively Designed for good heat dissipation, use lower speed for softer stones like limestone