Youha Silicone Diaphragm is a pair of replacement silicone diaphragms (also known as membrane) for The ONE Electric , The INs Gen 1 and Express PLUS Breast Pump backflow protectors.It is ideal to replace your silicone diaphragm every 2-3 months, and less if you pump frequently. Replacing your diaphragm frequently is essential in keeping your breast pump working in top condition for best pumping experience. Compatible with: Youha The One Electric Breast Pump Youha the INs Gen 1 Youha Express Cups Youha Express PLUS Cups Contains 2x diaphragm only.