Your options have never been better with Dr. Brown's Natural Flow Anti-Colic Options+ Narrow Glass Baby Bottle. The anti-colic internal vent system is clinically proven to reduce colic. Dr. Brown's bottles provide a more comfortable feeding experience for baby by decreasing spit-up, burping, and gas. The vacuum-free feeding is closest to breastfeeding and Dr. Brown's silicone nipples provide a consistent flow so baby 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. Dr. Brown's vent system is proven to help preserve bottle milk nutrients and aids in digestion for a better night's sleep. The silicone nipple, together with the internal vent system, offer a reliable and trusted bottle-feeding experience that makes Dr. Brown's the #1 Pediatrician Recommended Baby Bottle in the U.S.* Dr. Brown's Glass bottles are heat and thermal shock-resistant, which can withstand hot and cold temperatures, along with gradual temperature changes. Made to grow with baby, our bottle is designed to nourish through all of baby's feeding stages. Safe for use in dishwasher (top rack only), electric and microwave sterilizers or boiling water. BPA Free.