This natural feeding bottle has an anti-colic valve that flexes to allow air into the bottle, preventing vacuum build-up. Air bubbles move away from the nipple and into the bottle instead of baby's tummy. The naturally shaped nipple promotes proper latch-on, and the bottle features accurate feeding measurement markings and a dome cap. Its wide bottle shape makes for easy filling and cleaning. Bottle is made from Polyethersulphone (PES), which is BPA free. Dishwasher and microwave safe.