High Quality 304 Stainless Steel to ensure sustainable durability and to provide consistent use for many years. All of the lids are made BPA free to ensure that your body is safe from harmful toxins. Do good for your body and the planet by using a reusable stainless steel mug. Our mugs compactly holds a high capacity of liquids, making it easier to stay hydrated all day long. The tumbler's tapered shape and design is easy to grip and can be inserted into almost any cup holder