The Options bottle line comes with an internal vent system that has been shown to reduce feeding problems, preserve vitamins and help digestion. For your flexibility, the internal vent system can also be removed as your baby develops and is better at feeding. These bottles are known for reducing colic, spit-up, burping and gas. Proven to help preserve bottle milk nutrients vitamins C, A and E are critical for health in infancy. Good digestion is essential for babies, particularly newborns. Made of super-soft, high-grade silicone, each nipple level provides a different flow rate.