The set is supplied with 72 numbered disks that are stored on three brass racks. The brass plate A of the opaque disk revolver rests on the microscope stage. The specimen can be cemented to disk G which is placed in holder E. The arm C can pivot about point B. Turning the milled knob F results in rotation of the disk holder E via a fusee chain mechanism.The entire mechanism can swivel within drum D thus allowing the specimen to be viewed with any orientation.