The tumbler has double-wall vacuum insulation, which keeps cold drinks cold and hot drinks hot for hours. It also prevents condensation from forming on the outside of the tumbler, eliminating messy water rings, and prevents warm beverages from burning your fingers. The press-in lid stays in place with a silicone gasket, and has a slider to open and close the drink opening; it protects drinks from splashes and debris when taking them outside and on the go. The tumbler has a capacity of 12 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.