D1 material, the overall high temperature quenching, Hardness to HRC65, 50% increase in service life! High Quality 6pc 65mm Electric Magnetic Screwdriver Bits PH2 Ph Hex Shank Head Driver Bit head for long screws to join the high-strength magnetic magnetic ring, effectively prevent the process of off the phenomenon! the middle of the use of concave design, more torque, better toughness. The head of cutting, of bite when the operation, less damage to the, Manufacturer: Mcnhbdgg