The invention relates to a thermally triggerable indication or switching device, having a movable, mechanically preloaded slide which directly or indirectly triggers or actuates the indication or switching device, and having a preformed part which changes its state of aggregation under the effect of heat, the preformed part, in the functional state, being adapted to be arranged so as to block the movable slide. According to the invention, in the initial state, the preformed part is loosely located in a receiving space. For transferring the preformed part to the functional state, the slide is moved in a position such that a gap space opens between the slide and a slide stop, wherein the preformed part enters the gap space and the slide is simultaneously preloaded.