A simple, yet effective apparatus to demonstrate the working of the lungs. Two sacs represent the lungs, contained in a clear plastic enclosure which models the chest cavity, with a rubber membrane base which serves as the diaphragm. By making the diaphragm relax and contract the students can see how the lungs are emptied and filled with air. Comes complete with comprehensive student's and teacher's guides. Approx 13cm (h)x 17cm.