Baby can regulate the flow of milk with the Philips AVENT Classic Teat, which can lessen overindulgence and spit-up. By opening and letting air into the bottle, the special valve encourages healthy, active feeding while also lessening colic and fussing. Features of the Product more cozy feeding at the baby's preferred speed Because of the special teat valve, it's simple to latch on. clinically demonstrated to greatly minimize fussing The bottle contains air, not the baby's stomach. Compatible with Classic+ and Anti-colic Feeding Bottles with or without AirFree vent, this unique anti-colic system is BPA-free.