Philips Avent Anti-Colic Baby Bottles With AirFree Vent are designed to help reduce common feeding issues such as colic, gas, and reflux. The unique AirFree vent draws air away from the nipple, keeping it full of milk to help prevent air ingestion and allowing for upright feeding even when the bottle is held horizontally, which may help reduce reflux and support digestion. The nipple shape promotes a secure latch for comfortable feeding, while the integrated anti-colic valve in the nipple reduces vacuum buildup and directs air away from your baby s tummy. With few parts, the bottle is easy to assemble and clean, and the one-piece AirFree vent requires no special tools. The bottle can be used with or without the AirFree vent to suit your baby s feeding needs. Soft silicone anti-colic nipples are available in flow rates 1-4. Includes 3 anti-colic bottles (4 oz) with AirFree vents and Flow 1 nipples.