Specifications: Body Type: 360 degree rotating 45 tilt binoculars. Eyepieces - Two 10 x FN23 eyepieces supplied with microscope body. Optional 15 x FN15 and 20 x FN11.4 available to extend the magnification range. Auxiliary lens: 0.5x 0.75x and 1.6x auxiliary lenses available to extend the magnification range of the microscope. Working distance: 90mm Without 150mm auxiliary lens. With 105mm 0.5x auxiliary lens. With 45mm 0.75x auxiliary lens. With 1.6x auxiliary lens. Zoom ratio: 4.41. Diopter adjustment - On both eye tubes 5.6D-.72D. Interpupillary distance: adjustable from 52 to 75 mm. Optical system - Greenough. Item weight: 3.65 lbs.