At Dr. Browns, our focus has always been to create innovative feeding products to promote good health and optimal nutrition for baby. Designed by a doctor in 1996 and patented in 1997, Dr. Browns Natural Flow is the only baby bottle to feature an internal vent system that: helps preserve vitamins C, A, and E by minimizing oxidation of breastmilk and formula; provides positive pressure vacuum free feeding similar to breastfeeding; and helps reduce colic, spit up, burping and gas by eliminating negative pressure and air bubbles. Dr. Browns Natural Flow baby bottles are BPA free and contain no PVC, lead or phthalates, and have received numerous design awards and acclaim from the medicalmunity. In fact, many of our bottles go to hospitals, NICUs, and doctor offices. Most important, moms are talking and theyre sharing with excitement the improved feeding habits of their babies. In keeping with the standards of our baby bottle, Dr. Browns products offer a unique design that yields a better functionality for mom and good health for baby. To maintain a brand that moms can rely on, we place a heavy focus on product research and development to ensure every product achieves the best possible result. This means that we invest as much time as necessary to create quality feeding products with distinctive health related benefits. Two replacement silicone nipples, exclusively for Dr. Brown's Natural Flow Standard baby bottles. Level 2 is ideal for feeding infants 3 months .