Sizing guide for ergonomic rings

Hello,

I’m trying to figure out the sizing process for an ergonomic ring, specifically regarding the x3s model. My usual measurement is about 57mm around a circle. Should I simply go with one that has a circumference equivalent of 57mm, or is there more to it?

Cheers.

I think so. That seems like the standard approach. The oval ones haven't worked out well for me personally, but I remember that their sizing matches up with the O ring dimensions.