Dr. Brown’s Natural Flow Anti-Colic Glass 4oz Baby Bottles Dr. Brown’s Natural Flow Anti-Colic Options+ Narrow 4oz Baby Bottles w/ size 1 silicone nipples Come w/ 2 silicone bottle sleeves 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 slow flow nipples provide a consistent flow so babies can feed at their own pace The anti-colic vent system is proven to help preserve bottle milk nutrients and aids in digestion for a better night’s sleep In excellent barely used condition, all bottles and parts have been washed and sanitized