American Optical Stereo Star #570 stereo microscope.  It is in nice operating condition - parfocal and zooms straight.  The Teflon zoom gear was inspected and no defects were found.  It comes equipped with 10X widefield eyepieces, Nicholas Illuminator and trans-base.  The only defect is that the glass stage plate is not original and is slightly under-sized.  The zoom range is 0.7X to 4.2X allowing for total magnification of 7X to 42X.  The images are sharp.