Two replacement nipples for the NUK Smooth Flow™ Pro Anti-Colic Baby Bottle. The one-piece integrated bottle nipple & collar makes bottle preparation and cleanup easy. And because the nipple and collar is only one piece, there are no leaks, guaranteed. This newborn bottle features a unique nipple design that allows baby to control the flow rate for colic-free feeding. Our Smooth Flow™ Pro nipple with a Y-cut design adjusts the flow based on how your baby drinks, adapting to their suction strength, ensuring they will always have the right flow rate.