Philips Avent Natural Response Bottle 125ml CLOSET YARDAS S484 C ESPEJO 3C 4P. Natural Response Teat: The unique Philips Avent bottle nipple opening only releases milk when the baby actively drinks. Works like the breast: The teat releases milk when baby actively drinks, this is different from the traditional free flow teats. As with breastfeeding, it can take time for a baby to get used to this. Anti colic valve: The baby bottle is designed to keep air away from the baby's tummy during feeding No drip teat: No drip teat design prevents spills and lost milk Simple to use, easy to clean and quick to assemble BPA Free