Where can I buy ventilation ducting?

[llykstw]

I'm trying to connect a ventilation fan, with a circular 150mm outlet, to 100mm circular ducting (as there is already a 100mm circular hole available in the wall and I don't fancy redrilling a larger one), but I cannot find anywhere that will supply a 150-100mm circular reducer.
Can anyone help locate one??

Thanks!

 

[DAZB]

Go to the link below and type H31680 into the search box.
http://www.buildercenter.co.uk/build/default.html
Then if you click 'home' you can search for a branch near you. Good luck.

 

[llykstw]

Thanks DAZB - that certainly sounds like what I'm after (but £20!!!!!), and there's a branch just down the road from me