Advanced know-how nipples, specially designed for dr. brown's options natural flow bottles with narrow neck. Made from ultra-soft, high-quality silicone, without bisphenol – a.. \ \ Available in 6 different flow types, corresponding to the feeding needs at different stages of infant development. \ \ Instructions for use: \ \ Before first use: use clean hands and surfaces when handling. Wash all parts before use. Before first use, place the nipple in boiling water for 5 minutes to ensure its hygienic condition. Make sure the nipple hole is clean. \ \ Before each use: pull the nipple in all directions before each use to make sure it is not torn. Check it carefully, especially when your child's teeth are growing, and replace the nipple immediately if it shows signs of wear, such as cracks or a change in shape. Small pieces can enter the respiratory system and cause serious injury. Clean before each use. The nipple must be clean and unobstructed. \