The stainless mug features an electro-polished slicksteel® finish interior that is corrosion resistant and repels stains. The tight fitted flip-open lid with a safety lock makes drinking from the mug easy and prevents beverages from spilling. • stainless steel vacuum insulation keeps beverages hot or cold for hours • stopper disassembles for thorough cleaning • 2-step lid release process prevents excess condensation on the stopper from being flung off while the lid opens • air vent on the mouthpiece allows beverages to flow out smoothly, without gushing or overflowing • 1-1/2" wide mouth opening • heat retention: 189°f for1 hr. / 162°f for 6 hrs. • cold retention: 46°f for 6 hrs. • made of bpa-free plastic and 18/8 stainless steel