Pigeon 17347 S-type Nipple 1pc Box M is made from thick ultra-soft silicone material. The nipple has comparable elasticity to that of a mother's actual breast. The dome-like shape makes baby's mouth open naturally. It is super-stretchable with slow flow. Teat section has an "accordion-like" portion that enables it to stretch in response to the peristaltic movement of the baby's tongue.