Light-Duty 2.6 mm Swivel Blades (NOGA) All blades are made of high speed steel and have hardness of 62-64 RC, except Model N10 cobalt, with hardness of 65-67 RC. For fast, easy removal of burrs from straight and curved edges and all kinds of holes, including cross and deep. A comprehensive program to cover all your light-duty deburring needs.