1 Wide-Neck Bottle with 1 AirFree Vent #1 Bottle Brand2 Designed to Reduce Feeding Issues Colic, Gas and Reflux1 Unique AirFree Vent designed for Less Air Ingestion Nipple Full of Milk, No Air, for Easier Upright Feeding AirFree Vent is One Piece, Easy to Clean Clinically Proven3 - Reduces Colic BPA Free Choosing the right nipple Different flow rates to keep up with your baby's growth. The Phillips Avent Anti-colic bottles can be used with or without the AirFree vent - but they should only be used with Philips Avent Anti-colic feeding nipples. We recommend replacing nipples every 3 months for hygiene reasons. Nipple stays full of milk, not air The nipple stays full even when the bottle is horizontal, so your baby can drink in an upright position. This can help reduce reflux, aid digestion, and make feeding time more comfortable for you and your little one. 1The AirFree vent designed for less air ingestion. Our unique AirFree vent is designed to help your baby swallow less air as they drink, by drawing air away from the nipple. Reducing the amount of air your baby ingests can help with common feeding issues, such as colic, reflux and gas. Clinical studies have shown that the Philips Avent bottle reduces colic and fussing.³ A valve in the nipple prevents vacuum build-up. This means that the air stays in the bottle, away from your baby's tummy, which helps reduce colic, gas, spit-up and burping. ²#1 reusable bottle brand in United States and Canada. ³At 2 weeks of age, babies fed with a Philips Avent bottle showed a trend to less colic compared to a conventional bottle and a significant reduction in fussing at night compared to babies fed with another leading bottle.