Mate, I jast got some nozzles and they are 4mm. I belive there are also 6mm tails available. It's all listed here:
http://www.aquamist.co.uk/sl/plist/frm-4-USD.html
There is also list of distributers you can call.
This is all I can do for you. This forum is really informative but takes ages for a new person get helpfull answers as most piople here only visit this place few times a week.