The thermo mug is made of stainless steel.Double walls with vacuum isolation allow to keep temperature of contents for a long time (more than 4 hours).Rugged sealed housing design: 100% leak proof.Easy to use: opens with one hand at the push of a button.Wide mouth for easy cleaning and pouring.Convenient for car use.Made in bright colors, the thermal mug will delight you and last for many years.Cannot be washed in a dishwasher.