Dr. Brown's Natural Flow Level 1 Nipple is sized just right for newborns, offering a slow flow. Dr. Brown's Level 1 Nipple, together with the Anti-Colic internal vent system, is clinically proven to reduce colic. Dr. Brown's bottle and nipple provide a more comfortable feeding experience for baby by decreasing spit-up, burping and gas. This vacuum-free feeding is closest to breastfeeding and Dr. Brown's Slow Flow Nipples provide a consistent flow so baby can feed at their own pace. The breast-like nipple shape encourages a proper latch for a more natural bottle feeding experience and eases the transition from breast to bottle and back again. The Level 1 Nipple and Anti-Colic vent system is proven to help preserve bottle milk nutrients and aid in digestion for a better night's sleep. Made of super-soft, 100% silicone, the Level 1 Nipple fits all Dr. Brown's narrow bottles. The suggested age range for the Level 1 Nipple is 0 months+, but baby's preferred flow rate may vary. Safe for use in dishwasher (top rack only), electric and microwave sterilizers or boiling water. BPA free.