This unique device features three independently expanding sections in one housing for transverse as well as sagittal development. Each section can be independently activated. When an equal amount of lateral development is desired, turn the two lateral sections at the same time. If a differential amount of lateral development is needed, by turning one of the lateral sections you can get unilateral movement. This is an excellent screw when the size of the palate is large enough to handle its considerable bulk. It is not suited for narrow palates or younger patients.