Pigeon Peristaltic Plus Nipple is of perfect shape and size to fit into the sucking fossa of baby. Inner vertical lines strengthen the structure of nipples; making it collapse-resistant. Textured surface allows baby to latch on easily and securely. 100% silicone nipple; super soft and flexible, allows natural and smooth tongue movement. Air Ventilation System (AVS) reduces intake of gas, a potential cause of colic.