I tried the large. It has an unforgiving fit. Rock hard, no flex for odd shaped head. The sides that come down over the ears pinched my head like a vise. Too small for me, even at size L.
My wife wore one for a few months, but she gave up. Ear protection was poor for her.
We both moved onto a soft helmet that flexed to our head shapes. Plus not interfere with my prescription sunglasses. We eliminated loud wind noises from blasting past my ears. My ears ring from the howl of wind noises. This is the one that worked for us.
www.mysticboarding.com/products/impact-cap-2024?variant=47948271714648 BTW, we tried the Mystic Legacy too. It creates wind noise from the vents in the top of the head, plus it is hard and doesn't feel near as comfy as the version without the hard shell.