Holder: Holder for plain shaft is used in transmission and rolling industry, automated production line, automatic equipment, automation industry, CNC machinery, military machinery, measuring instruments, printing machinery, packaging machinery, paper cutting machinery, pharmaceutical machinery, glass machinery, engraving and milling machinery, engraving machine, cutting machine, 3D printer, laser machinery, medical equipment, woodworking machinery, textile machinery, industrial grade machinery, semiconductor industry, tools machinery, medical grade industry, CNC machinery, transmission machinery, precision measuring instruments, mechanical arm, parking equipment, etc,and other fields in which need precise path positioning.