Flow control valve allows baby to control milk flow Milk only flows when baby creates a vacuum Mimics natural feeding behavior: baby can feed, pause and breathe, similar to breastfeeding One size or shape nipple for all stages of breast milk feeding Made without BPA Breastfeeding is always best for your baby but sometimes it is not possible to breastfeed naturally. Our latest studies with researchers from the University of Western Australia show that creating a vacuum is essential to successfully breastfeed. Babies learn very early on that they have to produce a vacuum for the breastmilk to flow. Their natural way of sucking requires intensive work during breastfeeding! The Medela Calma Feeding Nipple and 8 Ounce Set with Second Bottle is an alternative to breastfeeding for mothers wishing to feed their babies with breastmilk. With Calma babies do not have to change their natural feeding behavior. Whether you breastfeed or use Calma the milk only flows when the baby applies vacuum. The Medela Calma Feeding Nipple and 8 Ounce Set with Second Bottle Features: : - Enables babies to maintain their natural feeding behavior learned on the breast. - Babies can drink breathe and pause regularly. - Supports an easy transition from the breast to the teat and back. - One size is sufficient for the entire breastfeeding period just as in nature. - The unique feeding solution for your baby - we recommend introducing a teat when breastfeeding is established - Natural feeding behavior encourages easy transition from bottle to breast - Calma doesnt leak. Vented nipple helps reduce gassiness - One size/shape nipple for all stages of breastmilk feeding Similar as with breastfeeding your baby can: - Drink pause and breathe in its natural rhythm - Create its individual vacuum through a combination of tongue and jaw movements - Retain its natural way of sucking which supports an easy transition from breastfeeding to feeding breastmilk with Calma and back to the breast. Includes: - 1-all stage nipple - 2 - 8 ounce / 250 mL bottle - 1-cap - 2-lids