The number one seller in baby bottles. Anti-Colic internal vent system is clinically proven to reduce colic. Decreases spit-up, burping and gas. Vacuum-free feeding is closest to breastfeeding and Dr. Brown’s silicone nipples provide a consistent flow so babies can feed at their own pace. The breast-like nipple shape encourages a proper latch for a more natural bottle feeding experience and eases the transition from breast to bottle and back again. Made from a BPA free material and comes in a 4 pack.