These bits have a consistent coating of diamond particles. The 2.35mm(3/32") diameter shafts are made from stainless steel. Used for engraving, fine detail work or grinding on ceramics, glass, hardened steel, semi-precious stones, porcelain and plastics. The ball point bits are supplied in packs of 2, in 1mm and 1.8mm diameter. The cylinder bits are 5mm x 1.8mm and the Lenticular bits are 5mm.