i recently picked up a nice 1954 Centec 2A, it came with quite a few tools, one I cannot identify.

The tool looks as though it should clamp into a dovetailed groove:

Possibly an adjustable stop?

Though I cannot see how it would attach to the Centec, The dovetail it should fit is about the size of my ML7 cross slide, though the knurled clamp wheel would obstruct fitting.
Any suggestions?
Thanks