U. Nardin dress pocket watch?

Is it fair to say that this is a dress watch (50 cm case w/o crown, Sterling), or was there another application? Can I assume the button above the crown is solely for opening the case? 1920s vintage? I'd be grateful for any and all information about it. Thanks in advance.

ken h.

movement:

dial:

Ken, I am not a Ulysse Nardin expert, but your watch looks like a typical "ordinary" example. It does not look like a deck watch and, being a hunter, it wouldn't be an RR watch by US standards. So, I guess that makes it a dress watch. As for the age, of my three Ulysse Nardins, your watch most closely resembles a 14k hunter that I date to around 1920. The movements seem identical except that my watch has a jeweled center wheel and a micrometer whiplash regulator. See the photo below.

I see that. Thanks!