Strech series 1,Super hardness 2,Materials: HSS M2, SKH9, SKD11 ... CNC milling machinepolishing machineHardness:HRC50°-60°Tolerance:+/-0.005’’MACHINE TYPE:Punching Machine If you are interested in our products, ... the material of screw you need.2. the head shape/type & recess of header punches you need.3. the ... example: M3.0,D12*25.5. the surface coating type,for example:Plain,Tin,Ticn,Tialn.6. it is ...