This is a flashgun model #280, which was used with Polaroid cameras model 180. It is a clip-on device, made for AG-1 flash bulbs and 100-series peel-apart packfilm.
According to the Land List, "The interesting part about this flash is that a spring-loaded rod presses against the camera body (the back part of the camera) so that the flashbulb socket moves in and out of the reflector as the camera is focused, thus altering the dispersion of the light depending on the distance to the subject."
The two alcaline batteries were removed and discarded owing to deterioration. It is in its original packaging.
This information and much more is found on the very useful Land List
website.