Vintage Snap On ratcheting adapter?

[Hiball]

I was hitting up some antique shops today and ran across this piece, it was marked as “3/4” Snap on”, but it’s clearly 1/2 on both ends. I know based off the script it’s early, and I’ve seen the #6 plenty of times, but the ones I’ve seen have a reduced collar on the female end. The only markings are the Snap on script and what I believe is patent pending below, I haven’t attempted to clean it up yet, Not sure I will at this point.

Thanks

 

[Oldtuleguy]

Looks like the second variant, pretty short lived, I think 15 teeth? Earliest to later left to right.