Offering this nice clean 4" Yankee Thread outside spring calipers in very good condition, with no rust, damage, no past owner's marks on it. It is a very early model, and it may have had a ball on the end of the threaded, rod originally like the later ones we have had, but this one has no end ball. It is marked by the maker "L.S. STARRETT CO. ATHOL MASS. U.S.A. PATENDED JUNE 2, 1887". It is a Starrett catalog number 80. It works just fine, with very good measurement tips, and threads for fine adjustment!