【Compatible For Breast Pump】Flange Insert 15 mm compatible with S9/S12/S9Pro/S12Pro Breastpump 24 mm Shields. It will reduce the 24-mm shield nipple tunnel down to Correct Size(not for 27mm shield). 【Suitable for 24mm Shields/Flanges Only】These breast pump accessories are only suitable for 24mm Shields/Flanges and cannot be used with other sizes of Shields/Flanges. Using coconut oil or nipple butter can reduce friction and make them easier to use. 【Safe Material】Made of food-grade silicone, the inserts parts are BPA Free, odorless, and 100% safe for use. It's vital importance to replace out your pump parts regularly. 【Easy to Clean】After each use, wash the replacement pump parts with warm soapy water and rinse them thoroughly. 【Choose the Right Size Flange Insert】The size of your flange is important for comfort and efficient pumping. Some mothers have the experience of nipple swelling while milking, so it's important to observe how your nipples look during a pumping session. While pumping, your nipple should not rub or feel squished inside the flange tunnel.