The NUK Nature Sense Baby Bottle has an anti-colic vent that helps to prevent your baby swallowing air. The bottle’s teat has several tiny openings which are modelled on the milk ducts in a mother’s breast. The extra-soft tip of the teat is particularly flexible and adapts itself to the mouth in a way similar to a nipple. The NUK Nature Sense Baby Bottle is made of polypropylene and is BPA-free.