The sizes (from side-to-side) when the clasp is closed on the twisted bangle are approximate:

L 7cm
M 6.3cm
S 5.8 cm
XS 5.4 cm

Example of size Small (close and open)

C BANGLES
 

Regarding the C Bangle, while it is indeed rigid, it does have the capability to be bent open or closed in order to better conform to your wrist. Initially, the bangle's opening is on the smaller end of the scale, measuring around 15-20mm or approximately 0.75 inches (with the caps on). The primary difference between the S and M sizes lies in the overall length of the bangle, but the openings are quite similar.

When attempting to open it, please keep in mind that this action will cause a more permanent deformation of the bangle's base and may require some effort. It's important to avoid going from no pressure to pulling forcefully all at once. Such a method may result in unintended bending. Instead, we recommend gradually pulling open the oval shape while engaging your core muscles, which may assist in prying it open to just the right point. Start small and repeat as nessessary. Avoid bending back and forth.