I was really hoping these replacement membranes would save me some money, but unfortunately, they just don't work with my Medela pump.

The moment I started pumping, I could immediately hear the suction failing. It makes this weird fluttering sound like air is escaping, and sure enough - zero milk comes out. Such a frustrating experience when you're already sleep-deprived with a newborn!

What's especially annoying is that they *look* like they should fit perfectly. The color difference from OEM parts didn't bother me, but the complete failure of basic functionality does. I even tried adjusting how I inserted them multiple times - no improvement.

After reading other reviews confirming the same issue, I realized this isn't just a defective batch. These membranes fundamentally don't create the seal needed for Medela pumps to work properly. Back to buying the expensive OEM replacements for me!