This BPA free bottle is designed to reduce most common feeding issues including colic, gas, and reflux. The unique AirFree vent keeps the nipple full of milk, not air, as baby feeds in a range of positions for easier upright feeding. By keeping the nipple full of milk, the AirFree vent helps baby ingest less air. The AirFree vent is only one piece, and is easy to clean without any special tools. The Anti-colic bottle features a valve that reduces vacuum buildup, and reducing air into your baby's tummy. The Anti-colic bottle can be used with or without the AirFree vent, giving you the option based on your baby's feeding needs. The extra soft silicone nipple is available in different flow rates for babies of all ages. The Anti-colic baby bottle works interchangeably with most of the Philips Avent range making it easier to meet your growing baby's changing needs.