This a very clean used inside spring caliper that is marked "CRAFTSMAN MADE IN USA" on one side. Although the mark "CRAFTSMAN" is not the maker, this tool was made in the USA, most likely made by Millers Falls Co. in Millers Falls Mass. during the mid-1900's.  It measures 4.7" long overall and 4" from the center line of the pivot joint to the tips. It is in very good working order, good clean threaded rod, and solid nut, very good pivot joint, the spring is still strong. There is no rust, a few minor stained area, no damage, and no owner's markings. A quality made tool, by a well known maker!