Hengsong Women Slim Arm Correct Back Posture Humpback Prevent Long Sleeve Shaper Polyamide Material: Polyamide; it's smaller one size as usual, pay more attention to size details before buying!!! Size M: shoulder 14.15-16.9-inch, sleeve 9.43-11.79-inch Size L: shoulder 15.33-18.09-inch, sleeve 10.22-12.58-inch