This unbreakable model is nearly 3 times the size of an adult heart. Three hinged "doors" through the heart wall open to expose the four pumping chambers and their valves. A segment of the trachea and esophagus are shown on the back of the heart. The heart can rotate on or be removed from its base. Numbered with 39 key features explained in accompanying study guide. Size: 7" x 7" x 15".