Features: Broad compatibility, suitable for traditional breast pump, plug-in breast pump, and wearable electric breast pump. 4 sizes of flange inserts suitable for different breast pumps: 15mm ,17mm, 19mm, and 21mm, ensuring that every mother has fitted shield. Practical for small-nippled mothers to use large breast shields, 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: 15mm:17mm;19mm;21mm Package List: 1 * Flange Inserts Note: 1. Due to manual measurement, please allow an error of 1-3mm. 2. As different computers display different colors, thank you for your understanding, the actual product color may be slightly different from the image.