1. This material (chemical name: 10Ni3MnCuAl) is plastic mould steel, Pre- hardened to 36-43HRC, and easy machining, never deformation; 2. EFER On ESR steel echibitws a high purity, is suited for spark erosion; 3. There is uniform hardness from the surface to the core; 4. Application: Plastic mould with mirror requairments, such as Vidicon, Radio, High-Fi equipment, transparency cover and film.