The soft ribbed design of the nipple makes it easy for baby's mouth to seal on the teat, allowing easy and comfortable feeding. Air goes into the bottle, instead of baby's tummy. The anti-colic valve flexes to allow air into the bottle, helping to prevent gas from going into baby's tummy. Secure and leak-free storage and travel. The bottle will not leak while feeding your baby and the dermal cap seals the teat for secure and leak-free storage and travel.