Dave, they can't be taken apart. I assume there is a led or some other similar type of lighting device inside.
Hmmm... wonder what would happen if I connected third lug to AC 120V ground? This would be academic curiosity since I am not going to run AC 120V ground into a low voltage breaker box.
I was just poking about and saw some similar breakers from other companies state the lighting voltage - 120V for singe pole and 240V for double pole.
Mike