group of assorted vintage american industrial solid steel factory machine shop ring-shaped or radial steel single track ball bearings fabricated by the u.s. ball bearing mfg. company, chicago, il. the outer and inner rings are comprised of steel and house steel balls with separators. overall size and configuration vary from one ball bearing track to the next. salvaged from an old chicago machine shop. priced for the lot. variable dimensions ranging between 1-4 inches.