The Soft Flex Silicone Nurse reduces the amount of air your baby ingests, making feeding time more natural and more enjoyable. Anti-colic valves in the nipple and in the bottom of the Soft Flex silicone base allow air to flow into the bottle. This reduces the amount of suction your baby needs to apply and decreases the amount of air ingested. Features: Revolutionary new soft air silicone base that reduces colic Soft, hygienic silicone allows mom to assist with feeding by gently squeezing the sides of the bottle The Natural Touch silicone nipple mimics the natural contour and size of a mother's nipple. This familiar shape and size allows for easier acceptance and proper latch on. Made of special, soft silicone that transfers the warmth of the fluid inside the bottle to mimic the natural warmth of mother's breast Medium flow nipple gently flexes and elongates naturally and allows your baby to position the teat at the correct angle for feeding Superior anticolic valves in the base of the nipple help prevent colic and soft nubs on the surface to massage baby's gums Made of 100% BPA free silicone