The base of the bottle is made from ultra-polished 304 stainless steel (18/8). All plastic components are made from polypropylene. We were the first company to have a 100% BPA free baby bottle line. The materials we use are also free of BPA, BPS, phthalates, PET, PS, PA, nitrosamines, melamine, dioxins and biologically harmful chemicals. We conduct regular testing to ensure the safety of our products. The nipple is made from medical grade silicone.