Dr. Brown's Natural Flow® Original Wide-Neck Level 2 Nipple is a medium-flow nipple, great for babies whose feeding has developed. Dr. Brown's™ Original Wide-Neck Level 2 Nipple works together with our internal vent system to help babies feed at a pace that's perfect for them. Each same-level Wide-Neck Nipple provides the same consistent flow rate, so both you and baby know what to expect. Together with the anti-colic internal vent system, the Level 2 Wide-Neck Nipple gives baby vacuum-free feeding that is clinically proven to reduce colic, decreases spit-up, burping, and gas, better preserves nutrients, and aids in digestion for a good night's sleep. The suggested age range for the Level 2 nipple is 3 months+ but baby's preferred flow rate may vary. Fits Dr. Brown's™ Original Wide-Neck bottles. Dishwasher (top rack) and sterilizer safe. BPA free.