Is he wearing a turtle neck?
I've always been confused about this look. Is the undergarment a type of turtleneck or is it a special kind of t-shirt? While I really like this look, I've never quite seen the garment without the jacket on over it? Seems like a long sleeved turtleneck would be quite stuffy. If I had a better build, I'd wear a button up shirt or t-shirt under the jacket because it would be (a) more comfortable and (b) more attractive. Maybe I'm wrong.