Through the years, Apple Watch bands have varied wildly in size. So when you are upgrading your Watch, you could possibly speculate whether 1 of your respective outdated bands will suit. The just-released Series 9 has two case sizes, 41mm and 45mm, which have been released with the Series 7, https://troysdnve.blazingblog.com/26767507/the-2-minute-rule-for-12mm-watch-band