In my ongoing quest for a workshop which i may use and enjoy I keep a keen eye out for any and all things I may need (or "need"...) on the Norwegian equivalent of Craigslist. I have bought some absolutely astounding things for relatively cheap over the years, and I do feel my latest score was just that. A big score!
Here it is:

Brand new looking set of Mitutoyo 0-150mm. Micrometers. the standards are mostly not used and i actually had to open the bag with the keys needed to calibrate:

All of it for the equivalent of 120-150 £ or thereabouts.
In the same lot I did, however, also get this:

And I really have no idea what it is. Here's the other imortant view:

And the label from inside the case it came in:

There is a very stiff spring which makes it hard to manipulate in a manner which gives a reading on the Mitutoyo dial indicator.
It seems to have been purposely built for some specialised task and the two chromed things on either side of the u-shape leads me to think something like maybe tread or wire and there's a wheel missing in the midle or some such. Anyone have any idea? Any help very much appreciated!