World's first patented no screw thread closure; the Hegen Press-to-Close, Twist-to-Open™ (PCTO™) innovation allows the bottle to be pressed on and twisted off conveniently with zero spillage. Air venting bypasses the milk minimizing formation of air bubbles and oxidation of precious nutrients. Built-in anti-colic air vent reduces unwanted air intake. Elliptical-shaped silicone teat closely mimics a mother's breast to simulate a real latching experience, making combining breast and bottle feeding possible. Off-centre teat enables your baby to feed in a natural upright position. Express, Store and Feed within a single container with interchangeable pump or adapters, feeding collars and storage lids. No wasteful transfer of milk necessary. Hassle-Free Cleaning: The smooth interior surface, wide bottle opening and minimal parts make cleaning exceptionally easy.