Dr. Brown's Natural Flow® Anti-Colic Options+™ Wide-Neck Glass Baby Bottles are designed to provide a comfortable feeding experience for babies. The anti-colic internal vent system is clinically proven to reduce colic, spit-up, burping, and gas. The vacuum-free feeding is closest to breastfeeding, and the 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. The vent system helps preserve bottle milk nutrients and aids in digestion for a better night’s sleep. These glass bottles are heat and thermal shock-resistant, dishwasher safe (top rack only), and BPA free. They are designed to grow with the baby and are recyclable.