So, there is a poll out there 38mm vs 42mm, I thought it'd be interesting to take wrist circumference into account. The poll is laid out to be wrist circumference / chosen Apple Watch size. I've based this from the sizing on the Apple website. While some combinations probably won't work e.g. 130-134mm with 42mm Apple Watch, I've included the options in case you are looking into third party straps. Feel free to make any comments.