GLASS ANTI-COLIC BABY BOTTLE. Anti-Colic internal vent system is clinically proven to reduce colic. Decreases spit-up, burping and gasDURABLE BOROSILICATE GLASS. Dr. Brown's Glass bottles are heat and thermal shock-resistant, which can withstand hot and cold temperatures, along with gradual temperature changesCONSISTENT FLOW RATE. 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.PRESERVES NUTRIENTS. The anti-colic vent system is proven to help preserve bottle milk nutrients and aids in digestion for a better night's sleep.BREASTFEEDING BOTTLE. 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 againBOTTLE GROWS WITH BABY. Dr. Brown's Natural Flow Anti-Colic Options+ baby bottle works best with the internal vent system in place but can be removed as baby's feeding develops - no need to introduce a different bottleSUSTAINABLE BABY BOTTLE. Dr. Brown's Narrow bottle is designed to nourish through all of baby's feeding stagesDISHWASHER SAFE. Safe for use in dishwasher (top rack only), electric and microwave sterilizers or boiling water. BPA-Free