Let me start by saying, these replacement parts are a lifesaver for any pumping mom! I've been using them with my MOMMED S21 for weeks now, and the difference in comfort and efficiency is night and day compared to my old worn-out parts.

The 24mm flanges fit perfectly without pinching (though one reviewer mentioned occasional pinching - I suspect proper sizing is key here). The silicone feels incredibly soft against skin - no more red marks after long pumping sessions! What really impressed me was how the anti-backflow design actually works - I can finally lean forward without worrying about milk spilling into the motor.

Performance-wise, I noticed better suction and output almost immediately after switching to these parts. The duckbill valves create strong suction while the milk collector cups prevent any leaks during wear. They've survived multiple daily washes and sterilizations without losing shape or getting cloudy.

However, I must address one concerning review about bugs in the packaging. While my sets arrived perfectly clean (sealed in sterile bags), this is definitely something manufacturers should quality-check more carefully. Always inspect new pump parts thoroughly before use!

At this price point for 2 complete sets, these are absolutely worth trying if you need replacements for MOMMED or compatible pumps. Just be sure to measure your flange size correctly and sterilize everything before first use!