Paper cups "to go" are a thing of the past. The stainless steel mug is double-walled and vacuum-insulated, so it keeps drinks hot or cold for hours. It is leak-proof thanks to a safety button: press to drink and release to close! Whether as a coffee mug on the way to work or as an insulated mug for tea and other hot drinks ? the Miracle Mug is durable and free from harmful substances.