Patented bottom vent keeps air at the back of the bottle as baby feeds Virtually no air mixes with the milk and gets into baby's tummy Prevents air ingestion for less gas, colic and spit-up Ergonomic angle allows for feeding in a more upright position, a more comfortable way to bottle feed Easy switching between breast and bottle Our anti-colic, anti-reflux bottles have a bottom vent which promotes air-free feeding. Fewer air bubbles means a happier tummy for baby! Our angled baby bottle design promotes the semi-upright feeding position, recommended by doctors to minimize reflux. The Most Like Mom® NaturaLatch® Nipple's raised texture and natural wide shape is clinically proven to help baby latch naturally. Promotes easy switching between breast and bottle feeding. BPA Free. Easy to clean and assemble.