From http://dgrespiratory.com/other. The McKesson Vitalor was a dry wedge bellows spirometer. A pen attached to the top of the bellows marked on a small sheet of graph paper that was attached to an electric motor-driven platen (the curved silver plate). The mouthpiece was permanently attached to the front of the spirometer. A reviewer later noted that it was difficult to clean sputum out of the spirometer.