About a year ago I ordered the same T-shirt in size L, it is very cool, I wore it at home and not at home and under clothes, very comfortable, but I lost a lot, it became too big. I decided to order 3 more pieces of different colors at once, all in size S, but the black one is clearly smaller than all the others, it is probably xs, in color it is blacker than the one I took the very first one. Blue and white fit perfectly, but I think the black one will be narrow and may wear apart over time. In short, the T-shirts are actually cool, the fabric is nice, there are no reels, but the size is very difficult to guess. I think if you need black s, take m, and everything else matches