Specificly desined for machining hardened steel after heat treatment up to 65 HRC. Made from super micro-grain Tungsten Carbide rods imported from Germany, and coated with special heat and wear resistent layer inveneted in Japan. When machining high hardness material with H series tools, you can apply faster feed rate to finish your tasks in shorter time. When machining softer materials, the ability to resist wear will increase total quantity of the workpices you can finish with earch cutting tool.