Teat section has an "accordion-like" portion that enables it to stretch in response to the peristaltic movement of the baby's tongue. The nipple's surface is very soft, yet it does not collapse easily. Made from thick ultra-soft silicone material, the nipple has similar elasticity to that of a mother's actual breast. The dome-like shape makes baby's mouth open naturally, supports its mouth softly and fits its lips gently.