The Nûby™ Fast Flow Feeding Nipple features a large valve opening that is perfect for juice. It's made of soft silicone and features a natural shape which feels more like a mother's breast. This natural shape and feel promotes healthy, active feeding and makes the transition between breastfeeding and bottle feeding easier. It also features soft nubs on the surface of the nipple which help soothe baby's tender gums during teething. In addition, the Nûby™ Fast Flow Feeding Nipple features anti-colic vents along the base which help prevent a vacuum from forming in the bottle. This reduces the amount of air the baby ingests, and thus, reduces gas and the chances of colic.