Available in 5 sizes (Small, Medium, Large, Extra-Large &amp; Multi-Flow) <br>Made of non-toxic food-grade quality silicone rubber. <br>Wide soft silicone rubber teat is shaped like natural breast nipple to provide your baby with the comfort and familiarity. <br>Special valve to help prevent gas build-ups and stomach discomfort. <br>Retain clarity after sterilizing and are nitrosamine free.