The classic anti colic bottle features the clinically proven avent valve system to help prevent colic the new ergonomic design makes it easier for both parent and child to grip the anti colic system is now integrated into the teat meaning less parts to assemble and less washing sterilising after feeding time the unique valve incorporated into the teat flexes with the rhythm of babys feeding allowing them to control the rate of flow the bottle is 100 leak free and all materials are 10