I have always love the large Moonphase watches especially those automatic ones. found a 1950's vintage high-grade 25 jewel double-adjusted triple date moonphase automatic with horn lugs when I visited Cheong gor. It has a Large 37mm stainless steel screw back case with four calendar and moonphase push buttons and fancy horn lugs , signed 25 jewel double adjusted triple date calendar moonphase automatic movement (Felsa calibre 693), near-mint signed silver satin dial with full arabic numeral markers, day and month apertures at 12:00 with moonphase aperture at 6:00, steel hands and sweep seconds with arrow-tipped date hand pointing out outer date chapter ring, acrylic crystal, 20mm black leather strap.
The great thing about the Gubelin Moonphase is in its size as its about the same size as the 8171making it a desirable size to view the details. I didn't know the rarity of this watch after I start searching for it online.
The calibre 693 was part of the second generation Bidynator automatics produced by Felsa, starting in the late 1940's, and was the most complicated movement of this series. The Bidynator series was the first automatic movement to wind in both directions, and represented a milestone in the development of the automatic wristwatch. Really love the case design, size, and the Moonphase.