This is a good quality stereo microscope. (Two completely separate optical paths at slightly different angles give a true 3-D effect.) It was made by the NSK (Nissho Seimitsu Kogaku SS) Optical Co. of Japan. It has coated optics and a 6x zoom range. With the included 8x eyepieces (by Wild of Switzerland), magnification is 8-48x. It also has a screw on auxiliary lens of .75x. Working distance is ~120mm. With the boom stand, weight is 25 lbs. According to its label, it can work at up to 240x (you would need a set of 40x eyepieces to do this).
This is the only NSK microscope that I have seen, but it’s optical quality is excellent, superior to some expensive Bausch & Lomb scopes of the same type. It seems to be at least 30 years old, but well cared for and smooth working. Great for studying meteorites.
The price is $250 + shipping. SOLD