1Soft Silicone Material: The flange sizing kit is made of premium silicone, which is gentle and secure and will not cause skin irritation, providing a comfortable and reliable breastfeeding experience for mom and baby. 2Universal Design: Compatible with a wide range of chest pumps, the chest pump flanges feature a multifunctional design that is easy to replace and userfriendly. There are 4pcs inside our set enough for your daily replacement. 3Leak Proof Design: The chest pump accessory with a unique shape design that prevents milk leakage and ensures a comfortable and efficient milk pumping experience for mom. 4Dual Use Functionality: Suitable for both manual or electric chest pump, the silicone flange insert offers flexibility to meet different needs, reducing nipple pressure and enhancing milk extraction efficiency, making it convenient for daily use. 5Nipple Protection: Designed to reduce nipple pressure and chest discomfort, the chest pump flange helps protect the skin and alleviate chest engorgement for a more pleasant using experience. 4 xFlange Inserts