Features Broad compatibility, suitable for traditional breast pump, plug-in breast pump, and wearable electric breast pump. 3 sizes of flange inserts suitable for different breast pumps: 17mm, 19mm, and 21mm, ensuring that every mother has fitted breast pump. Practical for small-nippled mothers to use large breast pump, avoiding nipple trauma or irritation. Made from food grade silica gel, no odor, friendly to mothers' sensitive skin, secure to use. A practical breast pump replacement for breastfeeding, making milk expression more comfortable and efficient. Specifications Color: White and transparent Material: Silica gel Product Size: 17mm/ 0.66inch; 19mm/ 0.74inch; 21mm/ 0.82inch Product Weight: 15g/ 0.52oz Note The milk pumps showed in the pictures are not included. Package List 3 * Flange Inserts