Clinically Proven: Less fussing especially at night* Less colic** Sleep and nutrition are vital to your baby's health and happiness Unsettled and irritable behaviour; known as fussing, is by far the most commonly known crying behaviour in babies. Clinical studies show that the Avent Bottle significantly reduces colic** and fussing*. Fussing is reduced especially at night*. Unique anti-colic valve The two piece anti-colic system consists of the Avent Nipple and adapter ring. As your baby feeds, the unique skirt on the Avent Nipple flexes to allow air into the bottle instead of your baby's tummy. Like natural breastfeeding your baby controls the milk flow. 0% BPA (Bisphenol A) This bottle is made from PP (Polypropylene)- a BPA-free material. To fit your baby's growing needs Five different nipple flow rates are available. This pack contains two nipples with two holes. * - At 2 weeks of age babies fed with Avent Bottle showed a trend to less fussing than babies fed with another leading bottle. ** - At 2 weeks of age babies fed with an Avent Bottle showed a trend to less colic than babies fed with a conventional bottle.