Those are all the common style of clock. I don't need one, but I'm always on the lookout for the rare push-pull clock, identifiable by its metal rear case. I have one, but I've never found one that still works.
Yes, the buttons can be pushed & pulled. I'm not sure what they do when pulled because...
Steve83 wrote
...I've never found one that still works.
But the mechanisms inside the clock for those buttons is mind-boggling.
Technically, I DON'T "have" that clock right now... I mailed it to my brother (who repairs MRIs for a living in FL) several years ago, and he hasn't sent it back yet.