4H (High Speed High Hard High Feed High-Efficiency) series is our company high speed high hard high feed high-efficiency series. The series for our high-end products masterbatch using premium quality bar imports of the extremely small particles, both high abrasion resistance and bending. Specially used for high speed machining of steel with hardness greater than HRC60. 4H series of introduction, opened the door of hard materials and difficult to process materials.