I have a newer Heyco Germany 21/32 socket. Occasionally run into some Chinese hardware that's supposed to be 11/16.
17mm fits but is sloppy.
If you throw a pair of calipers on it, it's .656" which is exactly 21/32.
There's a reason why so many broke...kind of a design flaw...they work fine until the vise gets rusty, or the slide gets mushroomed or cracked.
People crank on them too hard trying to get them unstuck, and it's just a thin casting that breaks easily.
Saw this on FB, thought it was fake, then saw it on O'Reillys website:
https://www.oreillyauto.com/detail/c/tank-tough/tank-tough-3-ton-floor-jack/tnk0/tt20231
Searched here and didn't see it mentioned. Anyone have one yet?