Our 11 oz. Black Color Changing Mugs provide a fun and unique way to greet the morning. Our color changing mugs are heat sensitive and actually transistion colors to display your image when exposed to hot liquid. When the mug is cold, it appears black, but when coffee (or other hot liquids) are added, the black color magically reveals your chosen image. In some instances, some chosen images will not be completely hidden but will have an overall black cast. Thesed make great novelty gifts for all occasions. Available in cases of 36 pieces.