Branca Menta Bitters (20% alcohol) is Fernet Branca with mint added.
It is made by the Branca company and was produced in the US at one point, until popularity died down.
Cooking Tips
Branca Menta Bitter can be used in mixed drinks, or drunk straight up on ice.
Substitutes
6 parts Fernet Branca, 4 parts creme de menthe.