I have an LED integrated taillight, as well as a Givi V46 top box with the LED high stop light. I had a Kisantech flasher on the original taillight, but it wasn't able to flash the top box light.
I bought a Healtech Brake Light Pro and fitted it into the appropriate wiring, and have it set up with a decaying strobe effect. The LEDs flash quickly enough to make this really eye-catching. A very good safety feature.
The unit is tiny, about half the size of a box of matches.