Three replacement silicone nipples, exclusively for Dr. Brown's Natural Flow Narrow baby bottles. Level 4 is ideal for feeding infants from 9 months. The Dr. Brown's BPA-Free Level 4 Narrow Nipples are part of a complete line of Dr. Brown's nipples designed to grow with your baby. Designed for infants, the super-soft, high-quality silicone construction ensures that the nipples are comfortable for young mouths, and they encourage positive feeding. These BPA-free nipples are safe for cleaning in your dishwasher's top rack.