Nikon V-PSP simple polarizer tat will fit the following Nikon microscopes: Eclipse E400,  E800, Laboophot-2, optiphot-2, 50I.and possibly the I80 and I90 microscopes. This hard to find unit carries the current Nikon product number MAN591920 and old product number 93657.  It fits over the field lens just below the condenser and is secured in place with the extension knob.. This unit was only removed from packaging  to photograph. All glass surfaces are pristine and new, free from fungus, dust, element separation and scratches. Thanks for looking!