The BPA-Free 11 oz. PES Medium Flow Bottle from Avent features a one-piece anti-colic valve system that is clinically proven to prevent colic and fussing, especially at night. This highly durable, easy to clean bottle is BPA-free and made of honey-colored PES material. The unique anti-colic valve flexes to allow air into the bottle instead of your baby's tummy. Like natural breastfeeding, your baby controls the milk flow. Includes two bottles, each with 3M+ medium flow nipple with three holes.