Focusing slide block designed to hold the stereo microscope body on machines or for special OEM applications. Rack and pinion mount allows smooth, precise focusing. Coarse focus mechanism incorporates a slip clutch and tension adjustment. Distance from center of holder to center of pillar is 27.8mm longer than other holders like F, FX, FS and FSC holders. Therefore, when using trinocular microscope bodies like EMZ-8TR or EMZ-13TR, it rotates smoothly without the part of straight tube protruded touching holder.