The patented ventilation system allows you to feed your baby with the Dr. Brown bottle with or without the ventilation system. With Dr. Brown's ventilation system, your baby benefits from all the health advantages: the ventilation system prevents the formation of air bubbles in the feed, thereby helping to prevent colic, spitting up, and gas. The patented ventilation system effectively reduces the oxidation of breast milk and formula, promoting the stability of essential nutrients such as vitamins C, A, and E, as well as lipids. The complete ventilation system of the bottle enables vacuum-free feeding, similar to breastfeeding. Some parents find that the Dr. Brown bottle offers an additional feeding method: it is fed in a similar way to most bottles with a ventilation system in the nipple. The ventilation system in the nipple ensures the right flow. Dr. Brown's bottle nipples are made of soft silicone and are shaped like a mother's breast. The large set includes: Dr. Brown's Options bottle with wide neck, 2 x 150 ml, Dr. Brown's Options bottle with wide neck, 3 x 270 ml, Dr. Brown's wide neck nipples, 2 x travel caps of level 2 x 2, and 3 ventilation cleaning brushes.