Has adopt coarse-fine design,circle 360 scale,calipers reading,RSM56-1 adpot precision bearing design,M6x0.25ultra fine teeth screw driver,high precision,good stable.the diameter of aperture is 26mm ,clear light,attached accessories,connect or fix other devices,RSM82-1A high precision,high-load.standard aperture suit to different indications ,and connect with stages coveniently .composited multi-dimensional stage