Let me start by saying these replacement parts saved me during a desperate late-night pump session when my original Momcozy M9 valves gave out. The diaphragms? Absolute perfection - they create that same satisfying 'pop' sound when sealing, just like the OEM parts.

Now about those duckbill valves... They're *almost* there. While they fit snugly and prevent backflow, I noticed the suction feels slightly weaker during let-down mode. After 2 weeks of use (pumping 4x daily), one valve started fluttering inconsistently. Not a dealbreaker, but worth noting for exclusive pumpers.

The real MVP here is the value - getting 8 valves + 4 diaphragms means I can rotate them properly. Pro tip: Mark each valve with a dot using food-safe marker to track usage cycles. The silicone feels identical in softness to Momcozy's, though the duckbills seem to wear faster (about 3-4 weeks vs original's 6 weeks in my case).

Cleaning is a breeze - no weird residue after boiling, and they don't retain soap smells. For occasional pumpers or as emergency backups, this kit hits the sweet spot between cost and functionality. Just don't expect *identical* durability to OEM duckbills.