Dr. Brown's Natural Flow Bottles feature a patented, two-piece internal vent system that works unlike any other bottle design. The system fully vents the bottles for vacuum-free feeding, similar to breast feeding. As baby feeds, air is channeled from the nipple collar through the vent system to the back of the bottle, bypassing the breast milk or formula. This positive-pressure flow minimizes colic, the ingestion of air bubbles, burping and gas. Dr. Brown's - Natural Flow 8-oz. Bottle, BPA-Free, 2-pack: Includes: Bisphenol-A free bottles Two 8-oz bottles with level one nipples Two 2-piece internal vents 1 nipple cleaning brush
