Main product description This doctor-designed bottle brings a unique patented system of optimal air suction that significantly reduces the occurrence of abdominal pain, vomiting, belching and bloating. An internal flow valve prevents air bubbles from forming in breast milk or other liquid. No vacuum is created, which helps to eliminate unpleasant internal pressure. Can be used with or without valve. Its shape mimics breastfeeding very well and is ideal for feeding breast milk or other liquids. Dr.Brown pacifiers are made of very soft, high quality silicone. Individual species differ in flow rates.