I have no clue! It's just super thin, and not structured at all, so it quite easily bulges in some ways. I personally prefer the jackets more substantial, but it's nice to wear something light every now and then. Don't know enough about the construction of a jacket to comment, really.
Thanks! It says Exclusive mohair suiting, woven in England. I actually don't know the make, but my tailor recommended it to me. He has a lot of nice mohair blends with the same feel, and it holds the crease amazingly. Not shiny at all. Seems to be my tailors standard pleat, but I like it. Haven't cared or thought of changing them