Material of the Langmuir low profile vise?

Just a quick question, it’s not massively important but I am curious, what material are the Langmuir low profile vises made out of? The official langmuir website states that they’re made out of “hardened steel” but doesn’t give any more specification than that, so if someone could help me out with this I’d greatly appreciate it. Thanks!

I don’t know the molecular makeup, but I love both of mine.