Rubber eye shield - long (D=35mm)

 For microscopes the resoluting magnification can be calculated by multiplying the focal lenghts of the objective lens and the eyepiece. Thus, a 2x objective lens and a 10x eyepiece gives 20x magnification. With the same objective lenses, but 20x eyepiece the magnification rises to 40x.
All of the eyepieces listed are for the standard 30.5mm focusers which is compatible with most of the stereo microscopes.

The 10x eyepiece with measuring reticle can be used to calibrate the microscope and perform measurements.