Brings you up to date
Produced in PRC
The plugin part can be opened by unscrewing the collar at the spring pin and gently prising apart.
Its a snap together fitting.
The two wires are black and one has white stripes on it and this goes to the centre terminal and so is Positive.
Here in Europe the striped wire is sometimes negative.
They really should say in case ( as I did) you need to splice the wire to lengthen it.