Package Content You will receive 10 pieces of flange inserts (13/15/17/19/21mm), 2 pieces of each size. The sufficient quantity can meet your daily use and replacement needs.Compatible with Our flange inserts can be used with most 24mm shields/flanges and are compatible with any S9 Pro/S12 Pro/S9/S12 wearable breast pump, such as with Momcozy S12 Pro/S9Pro/S12/S9 hands-free breast pump. Please note that our product is not sponsored or endorsed by, or affiliated with the brands it fits, including Momcozy, Medela, Spectra.Comfortable to Use The correct size of the flange insert is very important for comfortable and efficient pumping. Chose the flange insert with a suitable size so that your nipple won't rub or be squished in the flange tunnel. It's recommended that you replace the flange insert every 1 to 2 months.Premium Material Our breast pump accessories are made of silicone. BPA-free. You can use them with confidence.Easy to Clean Rinse the pump parts with warm soap water and rinse well after each use.