It's in two parts. A brass bit with a silver coloured metal ring around it.
The brass bit pushes out of the silver bit exposing the cable attachment. However, once it's a few years old, the brass and the ring are reluctant to let go of one another.
Usually, spraying a bit of WD40 around the joint, then using two pairs of pliers to twist the ring gently off of the brass bit works.
Take a look at page 4, items 39 and 40:
http://www.bingpower.de/download/datenb ... ype84e.pdf