Those are the American Optical ones, which, in theory, are the original ones.
Yes, correct. I had to refresh on the history, but that is absolutely true. AO was the first USAF contractor to supply them for aviator personell issue in the 1960s. RE joined them not before the 80s. Both are built to the same spec...
I found my mine:
Back then, I was too young (in my late teens) to realize or appreciate how incredibly well built they are. 100% American made during the Reagan years.
And I can absolutely tell if I compare them to my mostly Asian-made Hugo Boss or Puma frames.