KENT 12" Diam. Grit 150 Quality Electroplated Diamond Coated Flat Lap Disk wheel 12 inch Grit 150 Quality Electroplated Diamond coated Flat Lap Disk wheel Arbor hole : 1/2" (12.7mm) High Density Diamond Coating Flat metallic back intended to be clamped to a Master Lap. For grinding and polishing jewelry, glass, rock