Philips AVENT New Natural medium-flow nipples are designed to help babies feed from both the breast and the bottle. The nipple's wide shape is similar to the shape of a breast, and its soft, rounded nipple encourages the same peristaltic movements used to breastfeed. Twin anti-colic valves keep air in the bottle and out of babies' tummies, making feeding and digesting more comfortable and reducing colic. The nipple is made of soft, durable silicone and has a petal design that prevents it from collapsing while your baby feeds.