Supplementary lenses change the working distance, with magnifications less than 1.0x increasing the working distance. This can be particularly advantageous when working under the microscope or handling tools. Magnification factors greater than 1.0 decrease the working distance. The supplementary lens is attached using an M48 thread in front of the actual objective pair. Depending on the magnification factor, the magnification range of the microscope can be varied. Further adjustments can then be made with an additional pair of eyepieces, allowing for optimal settings for each application. This supplementary lens is compatible with the following Bresser microscopes: Advance ICD Science ETD 101.