I'm stumped

[MackDigger]

 

[Icewing]

Samsung telephone

 

[mojjax]

looks like something a veterinarian would use - please charge your phone

 

[trikikiwi]

looks like something a veterinarian would use - please charge your phone

I'm not sure of the size - first time I've seen a phone used as a measure
but I see what you are saying - just saying
However, why the chain? Ahhh, just got it - the subsequent swelling limited, ergo ...

 

[Subterranean]

It appears to be spring loaded and will open to a specific width, at which time, the chain stops it from opening further. Obviously meant to go around something, such as a limb, circular object, etc...and then use the tension of the springs to hold it on, kind of like a tourniquet or such. Weird...Sub

 

[Red-Coat]

Just tidying up some blasts from the past (including some very ancient ones), largely for the benefit of anyone searching the site for information.

That’s a vintage exerciser for muscle-building, often known in it’s day as the “iron shoe” or “iron horseshoe”. Several companies made them under different brand names.

https://www.oldtimestrongman.com/blog/2015/05/07/the-iron-shoe-exerciser/

https://www.oldtimestrongman.com/blog/tag/iron-shoe-exerciser/