I've found a couple of these wonderful old stencil wheels over time, and keep an eye out for them as I think they're just fantastic things. This very early one, with 1868 and 1871 patent dates, is just about the best I've seen, and looks to combine (pretty unusually from what I've seen) a copper wheel with a rotating brass arm. It is in excellent condition with a gorgeous patina, and completely useable should one want to put it to work again. There were a few different sizes and variations of these made; this is the largest I believe, including all the letters and numbers as well as handy extras (lbs, yds, $, etc.) Held together at the center with a black stained wooden handle, the arm on top rotates easily around the disc, with two windows for framing the letter or number to the be used.
14" across at arm; the disk itself measures 13 1/16" across. Just a little minor bending to the whee in a couple of spots, no real matter. Perfect hung on the wall from the handle or from a letter with the handle hanging down.