OMAX 20X-40X-80X Binocular Stereo Microscope with Dual Illumination System Head: 4 5degrees Inclined 360 degrees rotatable binocular; Eyepieces: wide field WF10X and WF20X; Objectives: rotational 2x and 4x Left ocular-tube diopter adjustment +/-5dp; Interpupillary distance: 2-3/16inch - 2-15/16inch(55-75mm); Working distance: 3inch (75mm); Working distance with optional 0.5x attachable objective: 4-3/4inch (120mm); Field of view at WF10X eyepieces and 2x objective: 3/8inch (10mm); Field of view at WF10X eyepieces and 2x objective with optional 0.5x lens: 3/4inch (19mm) Incident (upper) illuminator: 12V/10W halogen, variable inclination; Transmitted (lower) illuminator: 12V/10W halogen; Easy illumination mode switch: [both] [upper only] [lower only] [off] Variable intensity illumination; Tool-free focus knob tension adjustment; Frosted glass stage plate: 3-3/4inch (95mm) in diameter; White/black plastic stage plate: 3-3/4inch (95mm) in diameter; Power supply: 110V/60Hz (US and Canada) 5-year warranty against manufacturing defects