Internal plastic shell with hinge is built into ballistic nylon boot and flexes to conform to the anatomy of the ankle, which greatly enhances patient comfort and compliance. The upper portion of the internal plastic shell is incorporated into the eyelet lace closure to create an inner cuff around the tibia and fibula which resists separation of the tibia and fibula to help treat syndesmosis ankle sprains (high ankle sprains). ASO Ankle brace with Flex Hinge features figure eight nylon stabilizing straps and elastic cuff work in conjunction with the internal plastic shell to capture the calcaneus and resist inversion or eversion motion.For sizing Can be worn on left or right foot. Measure ankle circumference from the base of the heel to the dorsal ankle crease. Shoe size can also be used for a guide.