Ye the the base part is adjustable maybe not the dovetail part it's self.I’ve seen these in fixtures as a thickness gauge.Is the dovetail adjustable?
More likely to have been used to do rapid inspections of product on a moving line, either as a straight measuring device, or as a plus-minus comparator (by setting the zero point at a target dimension, and gaging the product to see if it is over or under the required thickness. The two pictures in post #2 show this.Ye the the base part is adjustable maybe not the dovetail part it's self.
I assumed it mounted to something with a base for QCing parts or use on surface plate?