30 pcs Diamond coated CYLINDRICAL burr (4MM to 6MM) New one box set of assorted 30 pieces of diamond coated cylindrical burrs / pointed head. All of them are cylindrical shape. 4mm (5/32″), 5mm (13/64″) and 6mm (1/4″) burr head (10 pieces each size) 1/8″ (3.17mm) shank and 1 3/8″ shank length. Suitable for dremel or other high speed rotary tools. premium type diamond coated in GRIT 120 (Medium) Suitable for glass, marble, rock or jewelry. Please add water for coolant when using those bits.