tiny cool thing

I was looking at the little old row counter I bought yesterday. It has a "band" in the middle of it, with a gap, and I could see markings, and I thought, "that's odd" so I moved it around a bit more and discovered this:

IT HAS A TINY BUILT IN TAPE MEASURE.

Inches only, of course (No idea how old the item is - could be as recent as the 90s, could be as old as the 50s, I'm guessing) and it's rather thin and delicate and I don't know how long it is (I only pulled it out to 5") but for something like sock knitting this would be genius to have.