A favorite fabric from Kinross, their bamboo knits have a double layer, one that fits closer to the body while the second creates a beautiful layer that drapes beautifully, so it wears in the most forgiving way.  This tank is a perfect layer under cardigans and blazers.  95% bamboo viscose, 5% spandex.  Machine wash cold, lay flat to dry.  Runs true to size.  Margot is 5'4" and wearing the small.