A classic german pong system which uses the GI AY-3-8512 chip from General Instruments, thus playing the 4 basic pong games + 2 shooting games, all in color. This particular model (406-6) was made in Hong Kong and sold worldwide under many different brands, here Sonico in Germany.
The two controllers are not hardwired to the system, but connected to the console via two connectors located on the front panel (small jacks). This means that when one of them died, it wasn't necessary to change the whole system.
The shape of the case is weird. It looks like a case conceived for a small computer. Indeed there's enough room for a small keyboard instead of the actual panel control, and the bulk at the back could have contained a mother board or any other hardware...
Actually, this bulk is used to store the controllers when the system is not used, and there's also the cells compartment.