That light was normaly on an arm that could be raised up on their hand held search light.
The search light had a 4 Volt sealed beam in a chromed housing to the front with a red painted housing for the 6 Volt battery.
There where two versions, one with only the front sealed beam and one that also had the arm to the rear.
The bulb was of the now obsolete self flashing type.
They also sold the flashing lamp as a stand alone unit as the one you have.