It is a Carlo Dona tool - of course.
They are referred to as "stamps" on his site - You can see them here. His tools have a reputation, well deserved, for being very, very well made. And, ahem, priced accordingly. The rest of his tools are on the products page.
I would suggest avoiding the "home" page of his website as it launches the quick-time player and a very large download that starts music playing. Unless you like that sort of thing.