How is this used?

[Joe O'Leary]

Cleaning up workshop and found a bag of these. About 1" wide threaded ¼-20 lock thread.
Couldn't find them on the web.
448592

[Brian Tymchak]

Look like t-nuts that slide in slots in t track. I have nuts like these on my incra router table fence.

[Joe O'Leary]

Brian, the threaded part is round, so it would rotate in t-track. Plus the holes clearly indicate that it's meany to be screwed to something.

[Dan Friedrichs]

Maybe intended as a mount for something? Similar to this?
https://www.mcmaster.com/11445T1/
For hanging pipe, etc?

[Joe O'Leary]

Maybe intended as a mount for something? Similar to this?
https://www.mcmaster.com/11445T1/
For hanging pipe, etc?

I think you're close. I have a few of the one you show. They come in handy for hanging all kinds of things, but are much bigger than this guy.
It's got to be for hanging something, though. Maybe copper pipe?

[johnny means]

It's just a screw on threaded insert. We used these by the thousands for trade show booths, retail displays, and other
work that requires simple setups and breakdowns. Google float nut.

[Lee Schierer]

Cleaning up workshop and found a bag of these. About 1" wide threaded ¼-20 lock thread.
Couldn't find them on the web.
448592

Those are rivet nuts used on aircraft. Two small rivets go in the hole to hold it in place. THey are called nut plates (https://www.aircraftfast.com/aircraft_nut_plates.htm)

[Keith Westfall]

Lee has it right. We used to call them anchor nuts, or nut plates. Riveted to the back of a panel and held in place with 2 small rivets. Places where you couldn't get a wrench and a nut on the bolt or screw.