Pigeon Peristaltic Nipple Decorated Bottle encourages baby to use natural sucking pattern. Peristaltic Nipple is ultra-soft and flexible to allow for natural and smooth tongue movement. Air Ventilation System (AVS) reduces intake of gas, a potential cause of colic. The bottle is made from polyphenylsulfone (PPSU) material with high heat resistance and excellent durability. Available in other designs and color.