Synchronised socket, double, for nativities

Synchronised socket, double (for nativity light effects).
This socket features two plugs, one to be plugged to a 220V connection and one to be plugged into a synchronised socket.
The two plugs work with an alternated rhythm: one works together with the one in which it is connected, and the other one works when the first one is off.
This device can be used with the speaking Natalino machine and in any other occasion when an additional synchronised socket is required.
Technical characteristics:
Power supply: 220V
power: 500W.