Shaz-zam:
http://cgi.ebay.co.uk/Hot-Bodies-C80...d=p3286.c0.m14
You need two of these, and some 4mm set screws to secure them in place (about 4mm long for the setscrews is ideal if my memory serves me correctly, though you can always grind them down if they are a little bit long). Some blue threadloc will come in handy too..