Maymom 17 mm inserts (Long) compatible with Medela PersonalFit/Spectra 24 mm shields. It will reduce the 24-mm shield nipple tunnel down to 17 mm. Also compatible with Momcozy/LegendairyMilk/Tsrete Wearable 24mm silicone cups. Maintain compatibility with most handsfree bra - Based on the Medela PersonalFit system. You can use most handsfree bra with your original 24 mm detachable shields having this insert inside. Can be compatible with Spectra 24mm flanges, Ameda Purely Yours 25mm flanges, Ameda Mya Joy 25mm flanges, Willow 24mm flanges, Lansino 24mm flanges. Momcozy S9/S10/S12 Wearable Breastpump 24 mm cups ( NOT for 27 mm M1 cups) Also fits freemie 25 mm cup to reduce its nipple tunnel BPA free, made of food-grade silicone. Maymom 17 mm insert to use with Medela 24 mm shields. It will reduce the nipple tunnel down to 17 mm. Great solution for small-nippled mothers using Medela Harmony, freestyle, Medela Sonata, Medela Swing-Maxi pumps.