Coarse Focus Block/Holder is a black focusing holder with rack and pinion mount that allows smooth, precise focusing over 55mm of travel. It is a coarse focus mechanism incorporates a slip clutch and tension adjustment. Fits 20mm diameter, 71mm long mounting post. The 84.2mm diameter opening accepts all EM Series stereo bodies.Focusing holders hold the microscope body and contain the mechanism that raises or lowers the body to focus on the specimen. Complete stands include their own focusing holders. But for other kinds of tasks, however, it may be necessary to mount the microscope body on a boom arm stand or directly onto a machine or some other surface. The focusing holders below offer a range of options for such applications.Applications:EMZ Series zoom stereo microscopes are the prefect modular microscope systems for a multitude of applications ranging from biological and industrial fields to educational and training situations. A wide variety of professional groups currently use the EM series product to their advantage: Biologist, Physicians, Geologists, Engineers, Dentists, Dental Technicians, Veterinarians, Paleontologists, Entomologists, Gemologists, Educators, Scientific Researchers, Quality Control Personnel, Quality Assurance Personnel, Assemblers, Forensic Document Examiners, Art Restoration Experts, Textile Specialists, Wire and Die Manufacturers, Environmental Specialists, Ophthalmic Specialists, Dermatologists, Metrology Personnel, Tool and Die Professionals, Circuit Board Rework and Repair Personnel, Aquaculture Professionals, Embryo Transplant Professionals, Horticultural Experts, Exterminators, Fish and Wildlife Departments, U.S. Customs Service, Semiconductor Manufacturers, Foresters, Pharmaceutical Manufacturers, Electroplating Specialist, Ballistics Experts, and more!.