M 
              Moth Man      Very nice shirt!
Keep in mind it IS wool, but its a nice thick fabric that keeps its shape and can still be tucked into loose pants if need be. It is also a bit stiff but that's actually good when it comes to the collar and over all appearance.
It is itchy, but just wear an undershirt and you will be fine (this is coming from someone with sensory issues. Its on me for buying wool, but i will be warm in the winter)
Also on sizing for people who, like me, couldn't find a tape measurer: I am an extra small in mens usually and the size small here was a little bit tight in some places, particularly when bending the arms and chest. Make sure you size up just incase. 
Overall great :)