These were used by Western Electric by their central office
installers.When I used one in the 70's you could still get the
cartridges for it.The cartridges had a tendency to expand and stick in
the housing.It had a heat capacity of at least 100 watts comparable to
an AC unit.Even if you compared it to a modern gas soldering iron it
would throw out more heat.We used them to solder connectors to the main
DC busbar.I should have permanently borrowed one,they worked that well.