The alloy steel jaws: hardness(HRC36-42) suitable for the wire from 10 to 24 AWG(0.2-6.0mm). 
The cutter: hardness(HRC48-52), can cut off copper or aluminum wire. 
Can crimp insulted terminals from 10 to 22 AWG(0.5-6.0mm). 
Can Crimp non-insulted terminals from 4 to 22 AWG(0.5-6.0mm). 
With adjustment screw, you can adjust the strength of stripping.