It is a steel material with the wonderful function made as a high-level steel material of high-speed steel. The hardening hardness is around HRc65 and the toughness is excellent. It is one of the factors that the blade do not nick even after chopping the dried bamboo.Proprietary, high speed tool steel, working hardness 62-66HRC. Similar to AISI M2 high speed tool steel. According to Hitachi, YXR7 has better toughness compared to M2 in 61-65HRC range.