OptiVISOR Interchangeable Lens Plate

Optivisor lens plates are easily interchangeable. So if you wish to work at a different focal length or a different magnification, simply buy an additional lens. 

OptiVISOR lenses are the finest crown glass, ground and polished to precision opthalmic standards.  Glass lenses have a blue frame. Acrylic lenses have a clear frame.

please note:
For best results, choose the lens the with the lowest power necessary to accomplish your task. This is because the greater the magnification you use, the shorter your focal length will be and the smaller your field of view will be. Choosing the minimal magnification ensures the best possible field of view and focal length as you work.