Hyperextension Back Brace | 4C Flex | mediHyperextension brace with cantilever closing mechanism medi 4C flex is a hyperextension brace. The product is exclusively to be used for the orthotic fitting of the lumbar spine thoracic spine and only on unbroken skin. Moveable hip bar for better comfort while sitting Available in 4 sizes with optional adjustments of the side bar length Easy to use with new developed button closer Width of chest bars is adjustable Also available as short version and