1.This material (chemical name: 3Cr2MnNiMo) is plastic mould steel, pre- hardened to 30-35HRC, and easy machining, deformation; 2.EFER On ESR steel echibitws a high purity, is suited for spark erosion and mirror-like production; 3.There is uniform hardness over cross-section of large size; 4.Cab be hardened again to 40HRC; 5.Use for large size and long life plastic mould.