Level up to fast nipple flow! Dr. Brown's Level 4 Nipple is our fastest flow nipple for 9m+. Dr. Brown's uniquely designed Level 4 Nipple is a fast-flow nipple that works together with our patented internal vent system to help growing babies feed at their own pace. Each Level 4 Nipple offers the same consistent flow, so both you and baby know exactly what to expect. Made of super-soft, high-grade silicone, the Level 4 Nipple fits both Dr. Brown's Natural Flow Bottles and Dr. Brown's Options Bottles. The suggested age range for the Level 4 nipple is 9 months+ but baby's preferred flow rate may vary. Easily clean this dishwasher (top rack) and sterilizer safe nipple. BPA free.