The Pigeon silicone nipple was designed based on advanced lactation research and study to provide the best for mothers and babies. These are super stretchy nipples to encourage baby's movement for breastfeeding. Thick and made of ultra-soft silicone, the nipple is flexible similar to that of an actual mother's breast. Dome shape makes baby's mouth open naturally, softly supports his mouth and fits gently on the lips. All nipples ensure a minimum amount of air smoothly in the baby's stomach during feeding to avoid colic.