There are 2 plastic underwire supports that support the rib cage and ribs. It can be used under your clothing and it’s made of breathable fabric. Indications Costa and sternum fractures Intercostal muscle strain Chest injuries and post-surgical purposes SIZE CHEST CIRCUMFERENCE(cm) S 70-80 M 80-90 L 90-100 XL 100-110 XXL 110-120 Declaration of Conformity CE