Philips Avent Anti-colic with AirFree vent bottles are designed to reduce feeding issues: such as colic, gas, and reflux. The unique AirFree vent is designed to draw air away from the nipple keeping it full of milk to avoid air ingestion. This vent also keeps the nipple full of milk even when the bottle is held horizontal, allowing for upright feeding. Feeding in an upright position can help to reduce reflux and aid in digestion. The bottle is easy to clean and assemble with few parts. The Anti-colic bottle features a valve, integrated into the nipple, 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.