The Medela Harmony Breast Pump is a manual breast pump designed for those occasional times when you are separated from your baby. The Harmony is the only manual pump that utilizes Natural Expression pumping for maximum milk flow. Natural Expression pumping was first introduced with the Medela Symphony breast pump, and more recently seen in the Advanced Pump In Style breast pump. It uses two pumping patterns to mimic the baby nursing. Mom starts using the pump in the Let-Down Mode which copies the rapid sucking action of a baby during let-down then, when the flow of milk is establisshed, she switches to Expression Mode which mimics the baby's slow, deep sucking. No other manual pump has these two distinct rhythms.