The Spectra S2 Plus Double Electric Breast Pump is a closed system, hospital strength breast pump with highly adjustable settings, and extras like nightlight and timer A closed system breast pump has a physical barrier between the milk and the pump, which ensures hygiene and motor performance 2 Phase Cycling with Let-Down Button to mimic baby’s feeding pattern Digital controls allow you to set both the speed and suction level Can be used to double or single pump Comes with flanges in 24 mm and 28 mm size for better fitThe Spectra S2 Plus Double Electric Breast Pump is a closed system, hospital strength breast pump with highly adjustable settings, and extras like nightlight and timer