Features • These Dr. Brown’s bottles feature a patented two-piece internal vent system that works unlike any other bottle design. • The vent system fully vents our bottle for vacuum-free feeding, which we call positive-pressure flow, similar to breastfeeding. • As the baby feeds, air is channeled from the nipple collar through the vent system, bypassing the breastmilk or formula, to the back of the bottle. • Air never mixes with the breastmilk or formula which minimizes oxidation and helps maintain essential nutrients like vitamins C, A and E. • Babies feed more comfortably because the vent system allows them to nurse without fighting the negative effects of a vacuum or the discomfort of ingesting air bubbles. • This helps to reduce feeding problems like colic, spit-up, burping, and gas. • The breast milk or formula flows freely, without nipple collapse.