This Harry Potter Heat Changing Mug is one of our all-time best selling products and is perfect for adding a touch of magic to any cup of coffee or tea. Cold, the mug shows the password to the Marauder's Map - I solemnly swear that I am up to no good - and some footprints indicating the students and teachers of Hogwarts walking around the school. When hot liquid is poured in, the mug transforms to reveal Moony, Wormtail, Padfoot and Prong's Marauder's Map. Once the drink is finished, the password to close the map - Mischief Managed - is revealed at the bottom and the mug returns to its original state as it cools. This ceramic mug should be hand washed only.