American Optical Model 561 stereo microscope transbase stand.  Three stands are pictured, but this sale is for one.  The AO #561 is for incident and transmitted light.  This stand accommodates either the Starlite or fluorescent illuminator.  Recessed knob in both sides of the base allows rotation and positioning of a built-in diffusing reflector to permit optimum utilization of illumination.  The reverse side of the diffusing reflector is a plane mirror.  A unique swing in/out lens system assures evenly balanced illumination over the entire viewing area at all magnifications.  It will accommodate the American Optical SetreoStar / Zoom microscope #569, 570 and 571.  These units are clean and the rack and pinion gears and doveways have been lubricated.  The mirrors are in very clean condition and each unit has a few minor cosmetic blemishes. Missing is the clear glass circular stage plate. Again, this sale is for one stand.