Package Content: You will receive 10 pieces of flange inserts in sizes 13mm, 15mm, 17mm, 19mm, and 21mm, with 2 pieces of each size. This quantity meets daily use and replacement needs. Compatible with most 24mm shields or flanges and fits various wearable breast pumps designed for use with S9 Pro, S12 Pro, S9, and S12 models. Note that this product is not sponsored, endorsed, or affiliated with any third-party brands, including but not limited to Momcozy, Medela, or Spectra. Comfortable to Use: Selecting the correct flange insert size is important for comfort and efficient pumping performance. A proper fit helps prevent nipple friction or compression within the flange tunnel. It is recommended to replace flange inserts every 1 to 2 months for optimal results. Premium Material: Made from BPA-free silicone, these breast pump accessories offer safe and reliable use. Easy to Clean: Rinse all parts with warm soapy water after each use and rinse thoroughly.