9 Level suction control. Different suction strength and speed can be set on left and right. 2 Phase function. Stimulation phase/expression phase. Anti-Backflow. To prevent the milk from going into the electric motor. Soft breast shield. Reacts to the pumping rhythm which mimic baby's suckling for maximum comfort and stimulation. Rechargeable battery. Built-in with high capacity rechargeable battery, up to 10 cycles at single full charge. Comfort and quiet. Low sound for more privacy. Bottle neck adapter. Suitable for wide neck and standard neck bottles. Vibrating suction. Help stimulate breast to produce more milk.