LOZAEVE 15mm inserts compatible with Momcozy S9 S10 S12 Pro / Paruu P10 R12 P3 / TSRETE / Rainyb / NCVI / Willow / Bellababy MiniO, Pocket / for Maymom / for Spectra S1, S2 / Medela (PersonalFit Flex, Harmony, Freestyle, Swing Maxi, Sonata, and Symphony) / kmaier / TSRETE / MomMed / NaNaLazy / NIRGU / Onlyeah / MomWills / MomWills / Freemie / for Lansinoh. It will reduce the 24 - 25mm shields/flanges nipple tunnel down to 15mm. | Seamless Compatibility For Optimal Milk Expression: Suitable for nipple diameter 12-14mm(after a pumping session), or measure the circumference of nipple base about 31.40 - 37.68mm before a pumping session. | Great solution for small-nippled mothers using large breast shields, Proper nipple tunnel fit is essential for comfort and efficient milk output. | BPA free, made of silicone material. Durable, clear, and comfortable. This accessory helps breast shields for more effective pumping and maximized milk expression while helping to avoid nipple trauma or irritation. | Maintain compatibility with most handsfree bra. You can use most handsfree bra cups with they original 24/25mm detachable shields having this insert inside. During operation, you need to squeeze slightly to make the Insert fully fit with the shield to achieve the perfect effect.