The ZERØ.ZERØTM bottle with an anti-colic bag works the same way a breast gland does. Its system eliminates air bubbles to prevent air ingestion, helping to reduce colic in babies. Its ultra-soft silicone nipple simulates the shape, length and feel of the mothers nipple. Slow flow: Allows small amounts of fluid to pass through. Recommended for the first few days of life, for feeding milk, glucose, or water.