... Unit.And for Linear shaft has following features,Meteria:GCR15Hardness:HRC62+-2Accuracy:G6Roughness:Less than 1.5mm(Rmax)Diameter:3-120Straightness Tolerance:less ... , WCS13, WCS16, WCS20, WCS25, WCS30, WCS35, WCS40, WCS50, WCS60, WCS80. Chrome plated Linear Shaft Diameter 3mm ,linear round bar,linear motion bearing Shaft ,Bearing Steel linear ball shaft