Dr. Brown's clinically-proven bottle is now available in polypropylene, so you get all the health benefits of Dr. Brown's…plus the peace of mind of going BPA-free! Unlike conventional negative-pressure bottles, this positive-pressure bottle prevents air from entering baby's system, reducing the risk of colic and gas pain. (The difference? While conventional bottles mix air with formula, Dr. Brown's special vent allows milk to flow continuously and automatically, eliminating air bubbles.) Each 8 oz. bottle comes with one patented vent, one Level 1 nipple, cover, travel disc, and cleaning brush. All plastic parts are also BPA-free.For more information, click here.