COS Women's Size Small Black Half Sleeve Cupro Jersey Dress.  This is honestly the craziest dress.  On the hanger it looks like a standard black jersey dress, on the body it becomes something entirely different.  On the inside of the dress there is a jersey band attached to each side seam (shown in picture 7), which creates the shaping shown in pictures 5 and 6.  The front of the dress is relaxed with the shaping created by the band which forms a batwing under the arms.  From the back all of that volume creates a softer more relaxed shape.