Maymom Maymom Pump Parts Compatible with Spectra S2 S1 Replacement Kit for Spectra Pump Parts 21mm Flange Duckbill Valve Tube Bottle Backflow Protector, Not Original S2 Accessories

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. Every mother was created differently. One or two sizes can't fit all. That is why Maymom develops more than 12 sizes of flanges spanning from 13 mm up to 36 mm to fit the average mothers and those mothers who need special sizes. For pumping comfort, measure your diameter first (do it after a pumping session), and then use the size selector of this listing to choose the size that is 1-2 mm larger than your diameter, which is measured AFTER a pumping session.