This is a very nice Starrett No. 83 YANKEE PATTERN style spring dividers marked, "STARRETT NO. 83" This is a 12" size, 13.5" long overall. This was the longest Starrett divider in the No. 83 model.  This No. 83 has the spring nut feature that allows the split nut to open and slide quickly to another threaded location for quick set up from size to size, then with pressure on the nut again fine adjustment can be smoothly secured by turning the nut that has now calapsed onto the thread rod.  This one is in very good condition, very lightly used, all the adjustments work fine the scribe points are sharp and like new. Nice quality! We are not positive when this one was made, but estimate the mid-1900's.  A super nice tool!