Objective : Expansion screws like Hyrax. Haas and other types. produce heavy interrupted forces which are unfavorable for dental movement and could be harmful to the tooth and periodontium. The other disadvantage of these screws is the need for patient cooperation for their regular activation. https://www.roneverhart.com/Neumann-KK-205-Supercardioid-Capsule-Head-Black-008654-p29875/