Dr. Brown's 8 Pack Natural Flow Level 3 Standard Nipple is made of super-soft, high-grade silicone. These medium-flow nipples are designed to fit Dr. Brown's Natural Flow Bottles and Dr. Brown's Options Bottles, providing a paced feeding experience for babies 6 months and older. The nipples work with the internal vent system to help reduce air intake and minimize gas or discomfort during feedings.