Your options have never been better with Dr. Brown?s Natural Flow? Options+? Glass Wide-Neck Bottle. From nipple to base, the Options+? Glass Wide-Neck Bottle makes for a comfortable feeding experience for baby and eases the transition from breast to bottle and back again. Starting at the top, the NEW breast-like nipple shape is correctly contoured for a proper latch and a more natural bottle feeding experience – perfect for switching from breast to bottle and back again! Each nipple is specially engineered to offer the same consistent, natural flow, so you and baby know what to expect in every feeding. Together with the anti-colic internal vent system, baby feeds without fuss. Plus, our glass bottles are made of pharmaceutical-grade borosilicate glass that is heat and thermal shock-resistant ? which can withstand hot and cold temperatures, along with gradual temperature changes.