Review on Spectra S2 & S1 Breast Pump Replacement Kit - 27Mm Flange, Duckbill Valve, Backflow Protector Compatible W Nenesupply Parts. by Jaie Bobin

These work just as good as the spectra parts. Everything fits fine, no issue with twisting onto the bottles. Haven't broken the back flow protector either, be careful and its fine.I will say I put a nene duckbill and nene backflow protector on my spectra flange and only got one ounce. The other side was all nenesupply which got 3 ounces. 2 hours later and the side I pumped on with the mixed products is aching!I'll only be using spectra with spectra and nenesupply with nenesupply from now on.