the air free vent is designed to help your baby swallow less air. The teat stays full of milk, even when horizontal, for upright feeding reducing the air a baby ingests. This can help ease common feeding issues like colic, gas and reflux.The Avent Anti-Colic Bottle SCF403/15 features a slow flow nipple that helps promote the health and comfort of your baby. It is proven to reduce colic and fussiness especially at night. The unique valve integrated into the nipple flexes of this Avent bottle allows air into the bottle, preventing vacuum build-up and preventing air into your baby’s tummy. The valve also flexes to their feeding rhythm so milk only flows at their pace to minimize overeating, spit-up, burping and gas. The extra-soft silicone nipple on this Anti Colic Baby Bottle is available in different flow rates for babies of all ages. It is easy to clean and this promotes good hygiene.hilips AVENT Anti-colic baby bottle with Air Free vent 4oz with a Newborn Flow nipple promotes the health and comfort of your baby. This BPA-free bottle. By keeping the nipple full of milk, the Air Free vent helps the baby ingest less air. The Anti-colic bottle features a valve that reduces vacuum buildup and reduces air into your baby’s tummy. The Anti-colic bottle can be used with or without the Air Free vent, giving you the option based on your baby’s feeding needs. The extra-soft silicone nipple is available. 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. We recommend using the Philips AVENT Anti-colic baby bottle with Philips AVENT Anti-colic bottle nipples. Includes 1 Anti-colic bottle with Air Free vent with Newborn Flow nipple.