The tinier the ruler the better as far as I'm concerned -- all the better for measuring little things! I've had a couple of 6 inch folding rulers made of bone, but don't believe I've ever coming across a brass one, and this one feels quite special. No mark anywhere on it that I can see, and with just the 1st and last inch divided into quarters, the rest just into halves. 19th c. I believe, and I imagine made for a very specific purpose, perhaps for an architect or draftsman.

6" l x 1/4" w and in very good antique condition. Light in weight.