No case. I used to use a case but I found it only managed to collect more debris than protect it.
Unless there is some kind of otter case or similar that seals it off, which would make it a bit more bulky than I would like.
I just question the dust rating of the button, sure dust won’t kill the watch, but it seems to affect the side button in my case.
It’s more noticeable when I don’t wear it because of the tan line.