INFANT FEEDING STAGE 2 Transition: Desgined for growing baby's way of feeding 4M+ The Stage Two NaturalFit bottle features an upright, straight nipple. At this stage in baby's development, four-month-olds generally have better head and neck control when sitting while supported. The round base is retained for easy latching. Designed for Easy Transition Between Breast and Bottle! Soft, flexible nipple mimics mother's breast Lips are well opened and latched onto the nipple as the gums move up and down & the tongue moves forward and backward Twin anti-colic valves help prevent air ingestion, gas and spit-up Flexors at the base of the nipple enhance elasticity Internal ridges prevent nipple collapse Our 8 oz bottle comes with an Adjustable Flow nipple. The flow can be adjusted for baby's needs: Slow, Medium or Fast Ideal for growing appetites 3 bottles in a pack BPA Free Clinically Tested Made in Italy