．Bamboo Charcoal Product．Absorb moisture, ventilate, help perspiration．Help preventing strain and sports injuries．Provide extra support to strengthen the muscles and elbow [ Measure Round Center ] S (19.1 - 22.9 cm) M (22.9 - 26.7 cm) L (26.7- 31.8 cm) XL (31.8 - 37.5 cm) 2XL (37.5 - 43.2 cm)