Dr. Brown's Options+ Fast Flow Wide-Neck Baby Bottle Nipple 9m+ x2 consists of a teat with a wide base perfectly suited to Dr. Brown's Options+ Anti-Colic Wide-Neck bottles. Specifically, this teat perfectly mimics the nature, shape, and curvature of the baby's mother's breast. This is because its curved shape is more flexible at the top and gradually becomes firmer towards the base. In turn, this allows the baby to comfortably grip the bottle and not get confused when switching to the nipple. In this case, this teat is especially suitable for babies who frequently switch between bottles and breastfeeding.