Focus mount set up the correct distance between the lens of the stereo microscope body and the top of your sample, in order sample to appear in focus when looking through the microscope. Microscope focus mount adjusted by Coarse and fine mechanism knob and tension adjustment. Other name focus mount focusing bracket focus rack focus block E-Arm Focus mount Focus Mount Hole Diameter 15.875mm Focus Mount Ring Diameter 76mm Focus Mechanism Rack & Pinion with Tension Control Focus System Coarse & Fine Focusing Distance 50mm in vertical direction With coarse focus adjustment E-Arm Focus mount with 76mm diameter ring with 15.875mm (5/8″) adapter can be mounted on any of our boom stands or articulating arm stands, and features Rack & Pinion coarse focus adjustment. 50mm focusing distance in vertical direction.