Superior grade 18-8 304 stainless steel vacuum insulated construction Copper coating on the outside of inner steel wall adds a 3rd layer of insulation Polished steel accents Thread on/off Carry Ring slide tab closure lid (straw compatible) Removable lid slider for easy cleaning Lid slide closure intended to help prevent splashing and to retain hot and cold beverage temperatures. Lid is not leakproof and won't prevent spilling Sleek tapered design fits most cupholders Made with 100% BPA free materials Keeps hot or cold for hours