half-hunter

noun1

1. •
   A pocket watch of the hunter style, but with a glass panel or hole in the centre of the lid, giving a view of the hands even when the watch is closed.

   • Securing me with one hand, he […] coaxed from a washleather fob hanging in company with a crucifix I imagine from his neck a gunmetal half-hunter, sprang open its case, held it to his eyes […] — 1953