The design was created in order to put your wrist/hand in a great position while throwing a CB.  The design eliminates some of the major faulty areas that pitchers can get into.  Lateral deviation, wrist extension, and wrist flexion are all movements that can create injuries as well as a bad shape to your CB.  The metal pieces are stiff enough to hold your wrist/hand in place.  They are also light enough to bend to create the perfect fit for the individuals hand.  The velcro allows you to adjust to the shape and size of your hand.