The tumbler has double-wall vacuum insulation, which can keep drinks cold for hours, and prevents condensation from forming on the outside of the tumbler. The lid stays in and straw protect drinks from splashes and debris while still keeping them accessible. It's the perfect drinkware for taking beverages outside and on the go. The tumbler has a capacity of 20 ounces and is made from durable stainless steel; it should be hand washed to preserve the vacuum seal. All materials are completely BPA free and should not be microwaved.