What is the ESPRO™ Dillinger Tamper made of?

Dillinger tampers are made from vacuum-hardened stainless steel. The black ones are plasma coated with a diamond-like coating. It was developed for the machining and aerospace industry (think space-flight, jet engines, machine-tools).  It is so hard that the hardness measurement is off the Rockwell hardness scale (the measurement scale used by engineers to decide how tough something is)!