This product is made by Maymom to fit spectra's S1/S2 pumps in addition to spectra 9 and spectra M pumps. It is known that using the correct size of flange (breastshield) in breastmilk pumping is the most important factor in achieving comfort and efficiency.
Maymom Pump Parts Compatible with Spectra S2 S1 24 mm Flange Tube Bottle Backflow Protector Not Original Spectra S2 Accessories Replace Spectra Duckbill Valve Spectra Bottle Spectra Price in USA