0.5X WD165 RF4 Auxiliary Objective Lens For Stereo Zoom Microscopes . Key features include: Magnification: 0.5X, reducing the original magnification. Working Distance: Increases the working distance, in this case to 165mm. Field of View: Expands the field of vision. Compatibility: Designed for trinocular stereo zoom microscopes. Purpose: Used in electronics repair, quality control, and other detailed work requiring magnification.