Travel Coffee Mug (20oz) Thanks to our double-walled vacuum-insulated insulation technology, keeps beverages cold for up to 12 hours and hot for up to 6 hours. Tall tumbler base measures 2.8 inches in diameter, fits most standard car cup holders. The BPA-free clear lid that seals the cup tightly keeps spills under control and allows you to see inside. The cup is made from 18/8 food grade stainless steel, durable, unbreakable, rust-resistant, and doesn't transfer the flavor of your beverages.