I too found the masks to be surprisingly small. I have a few disposable masks sitting around as well as an old N95 mask from 3M I used in Asia a few years ago. The Bihn mask seems smaller than all of these. I'll wait for a large in a not-brown color to order more.
On a side note, I'm watching TV and all the doctors seemed decked out with new PPEs and the nurses are stuck with trash bags and reused masks. No wonder they seem so upset. Also, while surfing around, I noticed that Europe has banned exports of all masks for quite some time now. Even the U.S. didn't end up going that route, despite threatening to do so. The current situation seems to be causing people to resort to animal instincts, which is sad. Hopefully the mask situation gets resolved soon.