Within nature there is the potential for both good and evil, for light and dark. Both must exist as neither can be anything without the other. Dual wolves entwined within a dream catcher representing Yin and Yang. Heat Change Ceramic Coffee Mug - Gift Boxed is made of Ceramic, 11oz -315ml using heat changing technology with cleverly designed artwork which fully reveals when a hot liquid is added. They come supplied in a presentation box making them a perfect gift idea..