The ZERØ bottle with an anti-colic bag works the same way a mammary gland does. Its system eliminates air bubbles to prevent air ingestion, helping to reduce gas colic in babies. Its ultra-soft silicone teat simulates the shape, length, and feel of a mother's nipple. Available in two capacities: 180 and 270 ml. 3 flow rates available: Slow flow: Allows a small amount of liquid to pass through. Recommended for the first few days of life, for feeding milk, glucose, or water. Medium flow: Allows all types of medium-density liquids to pass through. Ideal for milk, juices, and very thin baby food. Adjustable flow: Allows more or less liquid to pass through depending on the baby's sucking strength. Specially designed for combining breast and bottle feeding.