Zoom Stereo Binocular Microscope ZSM-111 Binocular tube inclined at 45 for comfortable viewing and rotatable through 360. Zoom Ratio 1:4. Extra wide field eyepieces SWF10x Paired. Magnification Range : 10x to 40x. Working distance 80 mm. regardless of magnification. Rack and Pinion focussing system. Image remains clear and sharp throughout the whole zoom range. Interpupillary distance adjustment from 55mm to 75 mm. Thermocol Box