An M-66 is about 6 feet tall and seems to weigh about 800 pounds (it's heavy enough to bend metal stair risers under it's own weight). The machines are white, with black sheathing covering the forearms. The hands are tipped with long (and sharp) claws. The head is topped with white "hair" that functions as a cooling aid. Two versions appeared in the Black Magic anime, one had short hair and generally looked male, while the other had hair to it's waist and generally looked female.