As best I can tell, it's a 5" diameter, open-coat, all-metal (steel? tin?) arbor-mounted sanding disc.
It's the only thing that will remove tar from brick on my house, and I really need to purchase more. No idea where this one came from.
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That looks exactly like a Porter Cable paint remover disk, at a glance. 24, 36 or 48 grit, $20 bucks or so.
The tool it's made for: the Porter-cable 7403 abrasive paint remover. There probably is a backing pad that supports the disc.
Not affiliated, don't own one, do own some other Porter-Cable tools, happened to notice these discs when looking for some sanding supplies once.
That looks like a wrapper for something that had a solid inner component. You can probably find something with a more solid backing plate, like this one (example only), with tungsten or diamond granules.