The stainless mug features a stainless steel vacuum insulation that keeps beverages hot or cold for hours. The tight fitted flip open lid with a safety lock makes drinking from the mug easy and prevents the lid from opening accidentally. • stainless steel vacuum insulation keeps beverages hot or cold for hours • 2-step lid release process prevents excess condensation on the stopper form being flung off while the lid opens • air vent on the mouthpiece allows beverages to flow out smoothly, without gushing or overflowing • tight fitted flip-open lid keeps beverages hotter or colder • a special manufacturing technique was used to make the body ultra-lightweight and compact • 1-1/4” (3cm) wide mouth opening • made of bpa-free plastic and stainless steel • heat retention* : 185°f for 1 hr. / 156°f for 6 hrs. • cold retention** : 48°f for 6 hrs. • 2.375 X 2.625 X 7.75 inches *rating is based on water at a starting temperature of 203°f (95°c) at a room temperature of 68°f (20°c) **rating is based on water at a starting temperature of 40°f (4°c) at a room temperature of 68°f (20°c)