Dr. Brown's award-winning Natural Flow Feeding System sets the standard for colic-free feeding. The patented internal vent reduces air bubbles and fluid in the ear. With the patented internal vent, air bubbles and in-ear fluid are reduced. The ergonomic bottles have an easy-to-read formula level gauge, and nipples are resistant to collapse. Connects directly to breast pumps. No expensive liners to buy! Easy to clean and dishwasher safe. This bottle comes with the standard level one nipple for newborns. Please order our Dr. Brown’s Preemie Flow replacement nipples designed specifically for the premature infant. Features: 4 ounces, Standard neck, Standard silicone nipple, Reduces colic, Compatible with breast feeding and breast pumps, Dishwasher safe, Reduces fluid in the ear, Reduces spit up, Reduces gas.