The photo flash reflexion does not allow to read the info.
The guts seem to be just a charger with lamp as the resistance to limit the charging current.
Though, I maybe wrong, as often as often happens.
It is OLD, I saw them 30 years ago, and HATE them because no voltage limit and its low charging current capability.
The was another one, but I do not recall if the one you have, was used as a poor "re-juvenator" not very effective but the name sold thousands of them.
I can not see the diodes if any, if no diodes, it is a very poor "re-juvenator"
The resistor heaters are good for a high ( 50 - 115 volts ) volts load .
Nando