Are they legal in the UK? If so, should I use one here?
The Wildlife and Countryside Act, which regulates the methods used to kill wild birds, prohibits the use of sound recordings for decoying.
It also prohibits the setting of a device calculated to cause bodily injury to a wild bird coming into contact with it, and includes any electrical device for killing, stunning or frightening.
The electric wing decoy is none of these things and is therefore not prohibited by the Act.
However, many wildfowlers regard the use of the device as unsporting and, as a result, some wildfowling clubs prohibit their use over club marshes.
Therefore, before you consider the acquisition of one of these devices, the onus will be on you to determine whether it is appropriate to do so and to ensure you do not breach any local rules.