Lansinoh Momma bottles were the only ones my baby would latch onto out of the 11 bottles I've tried. My main issue was that I already own a Spectra S2 pump and the flanges did not fit the Lansinoh bottles. Since both the Lansinoh and Spectra pumps are closed system pumps I crossed my fingers and ordered this pumping set in hopes that it would work with my Spectra pump. The part where the tubing fits onto the backflow protector worked perfectly with the tubing that came with my Spectra S2. Everything works great and I haven't noticed any differences in how much I pump with these compared to the Spectra parts. I love that now i can pump directly into the Lansinoh bottles!
My only minor complaint with these flanges is that the softer material around the flanges (the purple part that goes around the diameter) makes it really hard for me to place into my pumping bra. The all plastic pieces slide right into place but the rubber part on the flanges get stuck on the bra and sometimes creates a mess. If you don't use a pumping bra then this is not an issue at all.
I also tried to fit my medela flanges on this pumping set and if you press really hard it will fit but I didn't trust that with the weight of the milk in the bottles the flanges wouldn't pop right off so I wouldn't recommend mix and match with the Medela flanges.
Overall I'm pretty happy with how this pumping set works with my Spectra S2.