These are for determining your bracelet size (kind of like trying on different rings to determine your size). I used Pandora's Sizing Guide (https://us.pandora.net/en/size-guide/bracelets.html) as a starting point for the models.
View Original Source Files on GitHub
Common Sizes for OPEN Design (hole at the bottom for your wrist)
Common Sizes for CLOSED Design (fully-enclosed oval)
Common settings to change in Customizer (in bracelets.scad)
The author hasn't provided the model origin yet.