Not necessarily for explosives, or you might want to wire your explosive into eg a switch to ensure it triggers under the correct conditions. From TFV, they are

Not necessarily for explosives, or you might want to wire your explosive into eg a switch to ensure it triggers under the correct conditions. From TFV, they are an invention of a saboteur division. I guess you could use them for a number of other options, like tapping a line, although you'd probably be better off just twisting the wires in that scenario.