Shoulder width on the size 15/38 Inglese linen popovers, please. (I imagine the chambray shirts measure the same.)
Are the linen Niche shirts sized the same way as the winter ones? If so, I'm a medium with XL shoulders.
Rotas in 500 g cotton twill work very well in -20 weather. I hope the summer Rotas will be as cool as the winter ones are warm.
Are the linen Rotas stiff or washed? (I think they are stiff based on the pics.)
You may have a shorter-than-average neck, so mock necks work best for you. I prefer full turtlenecks because they reach just below my jaw line (without hugging). Mock necks are too short on me.Still, I wouldn't want a linen turtleneck.