These are made of plastic. They are very easy to use when you go out or when setting them up with a breast pump. I hope someone who needs them will use them (*^^*) Please note that the shipping method may be changed to Yu-Yu Mercari Bin. Pigeon baby bottle set of 4, with markings up to 160ml. - Brand: Pigeon - Quantity: 4 bottles - Cap colors: Yellow, Green Thank you for looking.