I wear a small one with the Carhartt sweatshirt. So I ordered a small and medium carbon heater (40% poly, 60% cotton). When delivered, the small one is too small and the medium one is too big. I washed the medium to try and shrink it and it is slightly larger than I would like. I'll try the 100% cotton colors in medium and wash them to see if they shrink more. I'm 5'8" tall, 180 pounds, 40" chest, no abs. I like that my shirt fits perfectly, isn't baggy, doesn't stick to the skin. But overall it seems to be a nice, fairly thick shirt but a bit rough on the skin.
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