The Philips Avent Anti-colic nipple flow 4 is our fast flow nipple, which is great for growing babies drinking from a bottle. The anti-colic valve integrated in the nipple is designed to keep air away from your baby's tummy to reduce colic and discomfort. As your baby feeds, the valve flexes to allow air into the bottle to prevent vacuum build up and vents it towards the back of the bottle. It keeps air away from baby’s tummy to help reduce colic and discomfort. The nipple shape allows for a secure latch and the ribbed design helps prevents collapse for uninterrupted, comfortable feeding. The anti-colic nipple is made of flavorless, odorless, soft, silicone that resists discoloring and stickiness, a BPA free material. Philips Avent Anti-colic nipples are available in different flow rates, to keep up with your baby’s growth. We recommend replacing nipples every 3 months for hygiene reasons. Use Philips Avent Anti-colic bottles only with Philips Avent Anti-colic nipples. Includes 2 Flow 4 Anti-colic bottle nipples. SCY764/02 Clinically proven to reduce colic and discomfort Nipple is designed not to collapse, for a secure latch and uninterrupted feeding Replacement nipples for Philips Avent Anti-colic baby bottles come in flows 1-4, to keep up with your baby's growth BPA free Use the Philips Avent Anti-colic baby bottle nipples with the Philips Avent Anti-colic baby bottle