product description It can be used for observing and testing various PCB circuit boards, LCD display panels, and metal metallographic structures. Its comfortable and exquisite mirror mechanism and easy and fast operation method make it the preferred choice for industrial optical testing instruments in industrial and mining enterprises and metallographic teaching instruments in schools. Product features: The infinite far flat field optical system, with a long working distance of the objective lens (40X objective lens working distance of 3.7MM), provides excellent optical performance with ultra-low position front coarse and micro motion operation, reducing user fatigue and making the human-machine relationship closer. The triangular integrated frame structure not only makes the instrument more stable, but also greatly saves limited working space. The plug-in bulb exchange device makes bulb replacement more simple, safe, and reliable Technical parameters: