Polyester for stretch but with a pique Cotton effect making it a perfect lightweight summer blazer. This notch collar blazer has light shoulder pads and princess seaming for a shaping effect. It is fully lined including the sleeves which are slightly cropped and have a notch to show off your bracelets or watch. Dress it up for evening with a shiny cami or wear it to the office. I think this is a 20 although the tag is cut out. I have the same jacket listed in white in a size 18 and this is ever so slightly bigger.