This bundle includes two Dr. Brown's wide-neck glass baby bottles with anti-colic vent systems - a 9 oz and 5 oz bottle. The anti-colic system is clinically proven to reduce colic, spit-up, burping and gas for a more comfortable feeding experience. The vent system provides vacuum-free feeding that closely mimics breastfeeding. The bottles come with Level 1 slow flow nipples designed for consistent flow so baby can feed at their own pace. The breast-like nipple shape encourages proper latching for a natural bottle feeding experience, easing the transition from breast to bottle. The vent system also helps preserve nutrients and aids digestion. Made of durable, thermal shock-resistant glass, the bottles can withstand hot and cold temperatures. They are designed to grow with baby through all feeding stages. Both BPA-free bottles are safe for the dishwasher top rack, sterilizers and boiling water. With two different sizes, this bundle offers options to meet baby's growing appetite while providing the trusted Dr. Brown's bottle feeding experience that makes it the #1 Pediatrician Recommended Baby Bottle Brand in the US.