This 2-pack includes two Dr. Brown's Anti-Colic Options+ Narrow Glass baby bottles with Level 1 slow flow silicone nipples, for newborns 0 months and up. Each 8 oz bottle is made of heat- and thermal-shock-resistant borosilicate glass that withstands gradual temperature changes. The clinically proven anti-colic internal vent system reduces colic, spit-up, burping, and gas, and vacuum-free feeding mimics breastfeeding with a consistent flow so baby can feed at their own pace. The vent system also helps preserve milk nutrients and aids digestion, and it can be removed as baby's feeding develops. Bottles and parts are BPA free and safe for the top rack of the dishwasher, electric and microwave sterilizers, or boiling water.