Not mine.
My one low shank Singer Professional Buttonholler is not marked at all.
Neither of my standard slant shank Buttonhollers are marked.
The Singer has the black wedge shaped metal body and is in a burgundy colored plastic box.
The Greist has the black hump shape metal body and is in the brown tweed colored box with the dark brown text on it.
Two of my low shank Singer standard Buttonhollers are marked with "straight" on the mounting place.
Both are the beige plastic bodied versions, one is in a green plastic egg the other in a white pasteboard box with it's picture on the front.
None of my other ones are marked.
Joe