12 oz stainless steel is vacuum double insulated.The double walled insulated cup keeps your drinks hot and cold.Liner of tumbler will not produce any taste and will not rust.Lid of double walled tumblers is made of ABS, and it comes with a removable rubber gasket, safe and friendly.A hole on the lid, straw friendly, leak proof design keeps drinks from spilling or keeps your drinks hot and cold longer.The 12 oz water tumbler cup features a coated exterior and ergonomically design, which allows you to hold it comfortably, and will not slide down to burn you, without a dot on the surface, bringing you a pleasant visual feeling.