Outstanding Ergonomic Design ST680/810 35°viewing angle, ST650 40°viewing angle, suitable for longterm sitting observation.330mm×300mm big stand, high stability , apply to all kinds of anatomy of specimen. Top Optical & Mechanical Design Greenough optical system, built-in rotating shaft zoom system.No tilting Image in left &right light path in complete pupillary distance ,No dizziness feeling after long time observing.Patent number: 201320807246.0Stereo angle for left & right light path is 12°, stereoscopic effect, large viewing field, high zoom ration. Excellent Technology And Quality High resolution, large depth of field, excellent color restoration and contrast.Operation comfortable(manufactured by high-precision machine, excellent assembly technology).High- end material(PC resin cover, aluminium alloy ,copper alloy parts, austenite stainless steel driving parts). International Level Appearance Design Elegant shape , high-end and integrated appearance design, comfortableoperation. Various Accessories,Complete Function. Different video output connectors, built-in digital imagemodel.Illumination optional: LED, halogen lamp, cold light source etc. (100V-240V wide voltage input).Various professional stands and operating attachments.