Have you or anyone else seen a vise like this one ? Base is 1/2 inch thick and 2 5/8 inch in diameter. Top wing nut allows you to change heads. The one in there is extremely small ( midge head ? ) and there were no extras.The second wing nut down allow you to take whole top half off.

The cam at the bottom allows the head to be put in different positions.

Although I haven't been tying jigs for a long time. I have tied flies for quite awhile. I have never seen anything like this vise. By the way there is not one making or any kind of lettering on it.