Contents: 2 - 8 oz standard baby bottles; 2 - level one silicone nipples; 2 - two-piece patented internal vents; 1 - cleaning brush; instructions. BPA free. Free of bisphenol-A. Simply the best baby bottle. Reduces colic, spit-up, burping & gas. Less oxidation helps maintain vitamins C, A & E + lipids. Patented internal vent system. Vacuum-free feeding like breastfeeding. New Research: A recent university study set out to measure nutrient levels in baby bottle breastmilk and formula. It was determined that Dr. Brown's fully-vented bottles help maintain levels of important nutrients. The Dr. Brown's vent system reduces air bubble oxidation of the milk, which is very fragile and susceptible to nutrient loss. Healthy Tip: Vitamin C, A and E, and lipids, or good fats, are all naturally occurring in mom's breastmilk and are critical for health and growth in infancy. Patented Internal Vent System: 1. Air enters the bottle collar and routes directly through the internal vent system. 2. The air channels through the vent tube, bypassing the milk, to the end of the bottle. 3. The vent prevents aeration of the milk, vacuum pressure, and nipple collapse. 4. Baby feeds comfortably while the milk flows freely, like breastmilk. Reduces colic, spit-up, burping & gas: The patented vent system eliminates air and vacuum to allow baby to feed comfortably and reduce many common feeding problems. Less oxidation helps maintain vitamins C, A & E + lipids: The vent system is proven to reduce air bubble oxidation of the milk to help maintain vitamins and lipids, key nutrients to baby's health. Vacuum-free feeding like breastfeeding: The fully-vented bottle design provides vacuum-free feeding, closest to breastfeeding, which can also help reduce build up of fluid in baby's ear. Made in the USA.