After measuring my wrist, ordered a large and I'm an average sized guy. Was a bit hesitant because of the other reviews, but I reached out to Studebaker directly to address the faulty clasp and stretching others noted. They assured me that I won't have either of those issues, and even suggested fixing it if it did.
I can tell you,.I'm not sure how this clasp can even fail, it really locks in place and takes a while to don and doff. The leather hasn't stretched and it's working out just great. Just be sure to remove this before showering. I love it.