The Morelli´s Screw are used in fixed or mobile devices, to expand or of the dental arches. Available in various sizes ranging from 5 to 13mm opening - Precise at each rotation of screw activation. - Screw the brake system avoiding retrogression and loss of activation. - Stability on the maxillary and mandibular efforts. - Locking the top of guide pins prevent the dismantling of the screw in case of excessive opening.