Created by a physician, Dr. Brown's bottles feature a patented internal vent system that eliminates the vacuum and air bubbles to help reduce colic, spit-up, burping and gas. The positive pressure design allows babies to feed comfortably, because the vent system eliminates the air bubbles and vacuum. Baby feeds comfortably while the milk flows freely, like breastfeeding. Helps maintain vitamins C, A E plus lipids. Easy to clean, dishwasher safe, BPA free . Includes 3 - 8oz bottles with Level One Nipples, 2 - 4oz bottles with Level One Nipples, 2 - Level 2 Nipples, 2 - Storage/Travel Caps, 3 - Cleaning Brushes. Five Sterilizer Bags are also included with this set. </br>Features: </br>Bottles help to preserve vitamins C, A, E and Lipids. Reduces feeding problems like colic, spit-up, burping and gas. Vacuum-Free feeding like breastfeeding. Steam cleaning bags are easy to use and eliminate 99.9% of most bacteria and germs. Contains 1 Standard Newborn Feeding Set and 5 Microwave Steam Sterilizer Bags.