1. Product content: You will receive 10 flange shields (sizes are 13mm, 15mm, 17mm, 19mm, and 21mm), with 2 pieces for each size. An adequate quantity can meet your daily use and replacement needs. 2. Compatibility: Our flange shields can be used with many 24mm shields/flanges and are suitable for various S9 Pro, S12 Pro, S9, S12 wearable breast pumps, such as Momcozy S12 Pro, S9 Pro, S12, and S9 hands - free breast pumps. Please note that our products are not sponsored, endorsed, or affiliated with the brands they are compatible with (including Momcozy, Medela, Spectra). 3. Comfortable to use: A flange shield of the right size is important for comfortable and efficient breast pumping. Choosing a flange shield of the appropriate size can prevent your nipples from rubbing or being under pressure in the breast pump channel. It is recommended to replace the flange shield every 1 - 2 months. 4. Material: Our breast pump accessories are made of silicone and are free of BPA. You can use them with confidence. 5. Easy to clean: After each use, rinse the breast pump parts with warm soapy water and then rinse them thoroughly.