This isn't a down vest. Right when I got it I realized it was too heavy to be a down vest and when I read the tag nowhere did it say it was filled with down but rather with synthetic material.
I am 5'9 160lb and got the medium. it fits a little bulky around the belly, it isnt an athletic cut. the arm holes are tight. I think it might be uncomfortable to wear this over anything other than a thin under layer.