Harmony is a single, manual breastpump designed for occasional time away from baby. 2-Phase Expression® technology is proven to produce more milk in less time.* The best selling manual breastpump.1 What is 2-Phase Expression Technology? Through research, Medela learned that there are two distinct phases of how babies breastfeed. Stimulation phase – When babies first go to breast, they suck fast and light to stimulate milk flow. Expression phase – After milk flow or “let-down” starts, babies breastfeed with a slower, deeper suck, bringing out more milk faster. With this technology, Medela breastpumps work more like breastfeeding babies. *When pumping at Maximum Comfort Vacuum™ in the Expression phase.