A best selling product, this Harry Potter heat changing mug is sure to cast a magic spell over your morning brew. Cold, the mug shows the password to the famous 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 & Prongs' 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. An essential for any Harry Potter fan. 400ml capacity.