This is heat activated so it is made specifically to react to you pouring a warm liquid in it. You can pour in coffee, tea or even hot chocolate into the cup in order to activate it. After pouring in the hot liquid the cup begins to change appearance! Slowly it will change and the battery will charge up! You can't help but laugh a little out of amusement for this transformation. We have made your morning happier and brighter in seconds just like magic! Heat-activated mugs are not only a great fun start to the day but they are also a great way for you to tell whether or not that cup of coffee you made has been sitting out for too long. Nothing is worse than drinking that cup of coffee you set down and it is ice cold!