JC3 is a dense fine grained rod that is machinable and rated to a high temperature (2400℃ Heat Treating). It’s properties allow for good electrical conductivity and typically used for electrochemical applications.JC4 is a strong fine grained rod that is machinable and rated to a medium temperature (735℃ Heat Treating). It’s properties allow for good density and strength when higher temperature are not required. Typically these rods are used for mechanical applications.