The RL configuration is the grouping of needles to perform line work.
M08: Thickness of the needle 0.25, with long taper finish, recommended for super fine lines.
M10: Thickness of the needle 0.30, with long taper finish, recommended long for fine lines. The sharpness of the long angle allows to work more time on the skin, with less trauma.
M12: 0.35 needle thickness, with medium taper finish recommended for regular lines and classic lines.