While this is not a mandatory accessory to own or use, it’s a handy instrument when it comes to light up your Minox photographs. More so, if you use flash bulbs, the way they used to back in the day. Starting 1961, these units were joining the Minox list of accessories for the Minox A/IIIs camera models, and they were popular.
Designed to be a continuation of the camera, made in the same style and from the same materials as the camera, the flash unit was the answer to portability of a Minox camera. A steel reflector, which was folded within the unit and extended by means of a vertical button sliding along the back of it ensured a dispersal of the light provided by the tiny flash bulbs.
Although it was designed with Mnox A/IIIs models in mind, it can be used with other models, such as B, C, BL. Mind, if put onto a Minox B, it will cover about 1/3 of the lightmeter window, if you have the Minox B-C/B dedicated flash unit for the Minox B camera (the one with a window in it, use that). Also, on BL, you should be careful not to put any pressure onto the meter’s button. Have a look here:
The flash was powered by a Eveready/Mallory 15V battery, and this model is still being manufactured but not mercury, of course. These here are the old type, not anymore available.