This is a vintage (Ca. 1970s) Brown & Sharp No. 599-579-4 dial calipers & depth gage, 0-6” range, .001 increments, Swiss made.  It has a 3” depth gage base and wood case.  The calipers show use (minor scratches and nicks, but everything works smoothly – all of the locks work great – the increments are clear.  I did multiple “zero return” tests and it returned to zero each time.  It has NO extemporaneous markings.  This is a SUPER addition to your metalworking tool box.