Came back to this one from the collection recently...
After sitting in the safe box for quite a few years, I pulled this one out recently.
The case design is a bit dated with the smallish crown perhaps but at 40mm fits me well. The model is the San Marco Gigante reference 279-50 which at the time reflected the 'large' 40mm diameter.
UN made 200 in platinum like this one and 300 in rose gold. Solid back which seems appropriate for the time.
The best feature of course is the guilloche of the anthracite dial. Catches light wonderfully.