a defibrillator for permanent external application to a patient , with a protective shell arrangement receiving a base unit with defibrillator components , an electrode arrangement connected or connectable to the shell arrangement , and a support device . an ergonomic adaptation to the person wearing the defibrillator is achieved by the defibrillator components being spatially combined into subsidiary modules , and the shell arrangement has several subsidiary shells to which the subsidiary modules are distributed and which are movable relative to one another and connected to one another mechanically and electrically .