Pigeon Glass Nursing Bottle is equipped with a peristaltic softouch plus nipple that encourages the baby's natural sucking pattern. It is made of polyvinyl sulfone material with excellent heat resistance to ensure reliable and prolonged use. It also features an anti colic air ventilation system, that minimizes swallowed air to ensure safety. The soft, stretchable nipple allows easy sucking and encourages the peristaltic motion of the tongue. You can even adjust it to control the flow of milk. The nipple allows the natural tongue movement of your baby and helps with effortless latching. The baby bottles are long lasting and easy to clean.