American Optical model 561 stereo microscope transbase stand with a missing mirror.  The #561 is for incident and transmitted light; however, this one is missing the mirror assembly.  This stand accommodates either the Starlite or fluorescent illuminator.  A unique swing in/out lens system is still present.  It will accommodate the American Optical StereoStar / Zoom microscope #569, 570 and 571. This unit is clean and the rack and pinion gears and doveways have been lubricated. The clear glass circular stage plate is also missing.