Is this a bezel remover?

[dieale2]

I got this tool from an eBay pack. I thought it was a bezel remover but looking at it closer, you definitely can't remove bezels with this. As you can tell from the title, I don't have an idea what this is. It looks like a custom tool that someone made.

The tool is a ring with two dovetails that is cut into the bottom. These dovetails are facing each other and have some sliding device sloted in them. There are two devices look like arms and these arms have three screws, two small ones on the top and one large screw on the bottom. The arms are held in place by a very small screw that butts up against the ring body.

There is a screw behind each arm and it looks like you would use these screws to apply pressure to whatever is in the center.

It's pretty heavy and somewhat crude but very functional.

[clockboy]

If the centre screws are with sharp edges it might be some sort of crude cannon pinion tighter. 

[dieale2]

They look like pretty normal screws to me. I don't see any sharp edges but I'll check again.