The Fresh Jaws Nipple Clamps from PHS International are made of metal. There is no odor or taste to the toy. The "clamp" section of the toy has a bit of black rubber to prevent the clamps themselves from slipping. This is a great addition, because no matter how hard you pull on these, they will NOT let go until you release them. The rubber itself has little "nibs" to help prevent these from slipping.
Thank you so much for your very informative review! I especially like how you spoke of the types of users who will enjoy this product the most.