Medela Breast Pump Harmony with FlexHarmony Flex Manual Breast Pump The Medela Harmony Flex is a manual breast pump designed with 2 Phase Expression technology, mimicking a babys natural sucking pattern. It operates in two modes: Stimulation Mode Short, rapid suction to stimulate milk let down. Activated using the short handle, ergonomically designed for quick pumping. Expression Mode Longer, slower suction to express milk once it starts flowing. Activated using the long handle. The