Foredom Diamond Ball, 4.3 mm Dia. 3.8 mm Long 3/32 inch Shank, Style A-PD26. Used on hardened steel glass precious metals ceramics stone and composite materials for a broad range of applications. Its plated blank is precision turned for even coverage and a strong bond. Conforms to ISO specs for medium diamond grade: 120-200 grit/100-60 micron. For use on hardened steel, glass, precious metals, ceramics, stone and composite materials in industrial, jewelry and laboratory applications and on hard and soft woods for carving fine detailing and texturing. 120000 RPM Max Speed.