What is the external diameter on a movement spacer ring?

So, the plastic ring on an old Squale diver cracked. It's super brittle so I decided to look for a new one.

I was going to order a replacement from Ebay but they were asking what the external diameter was. I was trying to Google, but am unsure which measurement they're talking about.



Would it be: 1) the diameter of the inner ring, or 2) the widest diameter of the entire ring?

I assume it's #2, but wanted to double check.

If you're interested, it's for an ETA955.114.

Thanks

Thanks Al!