Notable appearances: Batman: The Animated Series, Batman: Arkham City

When the Dark Knight needs to keep tabs on an enemy, but doesn’t want to follow them too closely, he usually slaps a miniature tracking device on their shoulder so he can follow their movements. Small in size and virtually weightless, Batman can pick up a signal from these tracers from blocks away and follow that signal to wherever the villain is heading. This gadget is most useful when following a lowly henchman back to his boss’ hidden headquarters. For an expert in man-tracking such as Batman, these mini devices are among his most important gadgets.