Suniceme flange inserts 21mm are breast pump accessories that fit most 24mm Shields/Flanges. It will reduce the 24-mm shield nipple tunnel down to 21 mm. Compatible with Momcozy/TSRETE/Medela/Spectra/Elvie/kmaier/Phanpy/Bellababy/NaNaLazy/KISSBOBO wearable breast pump 24mm shields/flanges (Not for 27mm shields). BPA Free, made of food-grade silicone material, safe for mothers and babies. The Flange Inserts can be sanitized with water steam or boiling water. The pump parts can be cleaned with warm soapy water. It is recommended that you replace the parts every 1 to 2 months. Correct size flange inserts help moms pump more comfortably and efficiently. It is normal to feel your nipples swelling while pumping, so we suggest observing the appearance of the nipples during the milking process. If you do not have a good experience during pumping, Suniceme flange inserts for different nipple sizes would be a great solution for you. Flange Inserts 21mm Compatible with Medela/Spectra/TSRETE/Elvie/Momcozy/Bellababy Breast Pump 24mm Shields/Flanges, Reduce 24mm Nipple Tunnel Down to 21 mm, 4PCS