A signal switching device including an interface having a video signal communicating unit, a DDC and an HPD, controlling connected device, or being controlled by connected device. Thus, the movable jaw is movable in the slideway smoothly by the repulsive effect between the magnetic members and the movable jaw or the main body, thereby facilitating the user operating the adjustable spanner. Thus, the brightness of images displayed on a screen can be made uniform regardless of distance to an LED. The presence sensing device, and rotational position of the operator support may provide input signals to a control module that controls the vehicle travel, load handling features, andor other features of the vehicle that may be selectively enabled, limited or otherwise controlled.