Wideband and multi-section probes (slugs) for slide-screw impedance tuners use means for mechanical limitation of vertical movement towards the center conductor of the slablines, in form of cross bar structures and/or adjustable screws or dowel pins, in order to prevent the probes from having mechanical/galvanic contact with the center conductor of the slabline. The limiting screws or dowel pins can be mounted on the probes themselves or on the vertical tuner axis. Fine adjustment allows optimizing the maximum reflection factor at various frequency ranges and probe sizes.