This 2-pack Dr. Brown's bottle bundle includes their designer edition 5oz/150mL anti-colic baby bottles with level 1 nipples, plus a 2-count pack of level 2 medium flow silicone nipples. The anti-colic internal vent system in Dr. Brown's bottles is clinically proven to reduce colic, spit-up, burping and gas for a more comfortable feeding experience. The vacuum-free design provides a flow rate closest to breastfeeding so baby can feed at their own pace. The vent system also helps preserve nutrients and aids digestion. The breast-like nipple shape encourages proper latching and eases switching between breast and bottle. The level 1 nipples are designed for 0+ month babies while the level 2 nipples are medium flow for 3+ month babies, but flow rates can vary by child. Both BPA-free nipple options are made of soft, 100% silicone in a wide-neck shape for easy cleaning. They fit all Dr. Brown's Options+ wide-neck bottles. The bottles and nipples are top-rack dishwasher safe, microwave and electric sterilizer safe. With anti-colic bottles and 2 nipple flow rates, this bundle nurtures babies through various feeding stages.