Advanced. Clinically Proven: Less fussing especially at night (At 2 weeks of age babies fed with an Avent bottle showed a trend to less fussing than babies fed with another leading bottle). Less colic (At 2 weeks of age babies fed with an Avent bottle showed a trend to less colic than babies fed with a conventional bottle). One piece anti-colic system - fewer parts. Long lasting & scratch-resistant bottle. No. 1 for moms worldwide. BPA free. Clinically proven to reduce colic (At 2 weeks of age babies fed with an Avent bottle showed a trend to less colic than babies fed with a conventional bottle) and fussing, especially at night (At 2 weeks of age babies fed with an Avent bottle showed a trend to less fussing than babies fed with another leading bottle). Sleep and nutrition are vital to your baby's health and happiness. Fussing (unsettled and irritable behavior) is by far the most commonly known crying behavior in babies. Clinical studies show that the Avent bottle significantly reduces colic (At 2 weeks of age babies fed with an Avent bottle showed a trend to less colic than babies fed with a conventional bottle) and fussing (At 2 weeks of age babies fed with an Avent bottle showed a trend to less fussing than babies fed with another leading bottle). Fussing is reduced especially at night (At 2 weeks of age babies fed with an Avent bottle showed a trend to less fussing than babies fed with another leading bottle). One piece anti-colic system. Simple one piece system means fewer parts to clean and assemble. 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. Long Lasting Bottle: This BPA-free bottle (0% bisphenol A) is made of scratch-resistant honey-colored PES (Polyethersulfone) material. To Fit Your Baby's Growing Needs: Five different nipple flow rates are available. This pack contains two nipples with two holes. Made in England.