FUNCTIONAL LUNG MODEL (3101) The unique and easy to use model features parts that accurately replicate the human structures' function during respiration. Pulling the rubber diaphragm covering the bottom of bell jar reduces pressure inside for, the balloon "lungs" fill with air. Push the diaphragm in, and the balloon collapse recreating exhalation. The' set includes an acrylic bell jar, Y tube, two balloons and rubber diaphragm with a knob for easy movement. Qty :