To view CAD drawings displayed in the viewer use the controls at the bottom right of the viewer: + = zoom in, - = zoom out, "home" image resets the viewer, the last button opens and closes full screen viewing. Clicking the CAD drawing will zoom in and will allow dragging. *note: some drawings may not accurately reflect current products. For more detailed, up-to-date information please call HIS Business Mfg. Co. toll-free at (800) 292-9831. We will be more than happy to help.