Some relatively recent acquisitions:
I could barely read the Cincinnati and Hargrave names on this clamp. It looks to me to be forged, and that screw is heavy and quick acting; I suspect if you want to make darned sure something four inches thick is Definitely Clamped, this would be a good choice. Nothing gizmotic; just a serious clamp.
We then move to some little ones, also Cincinnati (the name doesn't appear as clearly in the photo as I'd like). The Hargrave H-in-a-circle is present, but they don't say "Hargrave;" maybe they felt there wasn't room.
Forged, again, and heat treated, too! 1-1/4" or so capacity.
I don't see very many 2-1/2" C-clamps, so it was interesting to come home from one day of wandering with three, all Brink & Cotton brand. I've been unable to find any chronology of logos for this manufacturer, so I don't know if I've arranged these by age or not; but it's interesting to see how the design differed over the years, while the model number stayed constant.