Soft stretchy fabric. Love how it feels! Adds a certain pizzazz to your outfit! I love it! I'm 5' tall, 128lbs, 32D bust,  26-28 low waist (depending on brand), my arms are thicker than the average girl my size (which makes it hard to find items that fit and look as it should on me) and the small fits perfect for me. The material has a good semi stretch to it (it isn't 100% elastic but it does have a good stretch ability to it)