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.
masonryrepairsandingtools
Best Answer
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.
Here's the pad:![Backing pad](https://i.stack.imgur.com/8UhOT.jpg)
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.