Otoaworks COBALT CAC622 Annular cutters have additional cobalt added for much greater wear resistance, although harder, will give longer cutting life in mild steel and better performance in more difficult materials. The extra added cobalt enables to drill in Stainless steel tough & harder steel easily. Available in weldon shank and universal shank. Otoaworks also produces 8% cobalt cutters with 35mm - 55mm.