A small device to flash lights on and off.
It is suitable for use with lighting rated between 30 and 60 watts. 200-250 volts.
Probably intended to be used with Christmas lighting or for shop windows.
Flashing a lamp on and off continually is the quickest way to destroy it.
The heater is in series with the lamp, which makes it dimmer and as a side effect extends it's life.
As the strip heats up, it bends away from the contact, and the circuit is broken. The strip then cools until the circuit is connected again.
This repeats endlessly.
This item is shown working, and is dismantled to show the internal mechanism. View this video on Youtube.