This is a nice clean steel outside spring caliper that is in very good working condition with about an 6" capacity (a bit more depending on your application), and will close to 0 also. This caliper is marked "ATHOL MACHINE CO. ATHOL MASS. U.S.A.". Athol was purchased by The L.S. Starrett Co. in 1905. The is a few small areas that have minor staining or darkening on them, no rust now. A nice clean, ready to use, colectible tool from the turn of the century!