Evenflo nipples manufacturer of silicone with a conventional pressure-sensitive response meant the child and respond with the right amount of air intake and liquid gas reduction micro. Soft and flexible, the pressure baby nipples CustomFlow perceive and respond with the right amount of fluids. Micro Air Vents prevent nipple collapse and keep air out of the belly of the child. 4 Silicone Nipples – Medium Flow (for children 3-6 months)