First off I thought that I had wrote a review for this coffee mug and, after looking on my blog noticed that I hadn't....ooooppppssss!!! Sorry!!! So, about this mug it is SUPER SUPER Cute!! You add hot water and, the little pig shows up. Once, it's cooled down it goes slowly goes back to the black. It takes probably about a minute or, a little less for it to change once, the hot water, cocoa, coffee, etc. are in there..But, it does actually work! Pretty AWESOME!!!