This model has a vertical V-shape jaw to hold round-shaped workpieces of various sizes.
The optimal workpiece sizes are given in the Dimension drawings (see Dim. in the table above). Please note that when machining a workpiece with a diameter larger than maximum given in the Dimensions drawings, there is a line contact between the jaw and the workpiece, and the jaw is likely to leave marks on the workpiece surface.
RMS-V has two such jaws, RMS-VS has one smooth jaw (photo).