Natural Response Nipple: The bottle features a Natural Response nipple with a unique opening that only releases milk when the baby actively drinks. This supports the baby's unique suck, swallow, and breathe rhythm, mimicking the natural breastfeeding experience. AirFree Vent: The bottle is equipped with an AirFree vent designed to keep air away from the baby's tummy. This helps provide extra protection against colic, gas, and reflux by reducing the ingestion of air during feeding. It also allows for upright feeding, which can further help reduce feeding issues. Comfortable Feeding: The ergonomic bottle design makes it easy to grip at any angle, ensuring maximum comfort during feeding for both the baby and the caregiver. Overall, the Avent Natural Response Feeding Bottles with AirFree Vent offer a solution for parents seeking to provide their babies with a comfortable and colic-free feeding experience, while also supporting their natural feeding rhythm.