How does a chastity belt lock work?

Greetings everybody. I've been thinking more and more about chastity belts and everything, but one thing just has me confused: how do the locks works?

I'm talking about locks like this:

Notice the gold padlock, and the shackle is locked around a sort of button. I imagine there is more than meets the eye here, but I'm completely confused as to how it works.

If anyone has this sort of lock, I would love to see how it's assembled. I'm not asking for pictures of you putting it on or taking it off (although those would be great), I'm just asking for some pictures showing how locking the shackle around the button locks the entire belt together. The only thing I can offer you for doing this is an internet high-five, maybe fake internet cookies.

Thank you to all,
Kaito

I'm not understanding. I understand how the button could cover a post or something, but I still don't get how locking the shackle around the button locks it in place

This is considered a female style, the reason for the text on the side is that it was the first picture I found that clearly showed the lock. But male belts can be made in this style