Size Guide

If you are a smaller adult (5'1"-5'7") with an average size face, you should get M. If your face is bigger than the average of your height or if you have a beard, get a bigger size.
If you are a bigger adult (5'8"-6') with an average size face, you should get L. If your face is bigger than the average of your height or if you have a beard, get a bigger size.
If you have a longer and larger face, or you wear a beard, you should get XL.
When in doubt, get the bigger size. The adjustable ear/head loops will enable you to tie the mask at the right width for your face and you can still wear the mask even if it's slightly big.