Duct Piping - 4" Flexi & 6" Rigid

Dr_Colossus

Before I go trapsing around builder providers again with much time wasted and resulting frustration any advise on where in/near Dublin 15 I can get some 4" flexi ducting. Perhaps electrical stores selling extractor fans are a better source and more reasonable in price? Will need 4 meters of it to connect an under stairs toilet fan to an external vent (no condensation or grease to worry about so flexi ducting would be fine plus will help avoid some piping and electrical cables en route). Have floor boards up at present for a different purpose and notice original builders installed the external vent and extractor fan but just used the void between the joists as the connecting vent.
Something like this perhaps but where in Dublin to source.
https://www.amazon.co.uk/d/Ducting/ALUMINIUM-FOIL-FLEX-DUCTING-VENTILATION-100MM-10M/B0192CRM2K/ref=sr_1_2?ie=UTF8&qid=1491251715&sr=8-2&keywords=4%22+flex+ducting

Another issue, there are vents in all the rooms but again nothing connecting the external vents to the internal grills. Although the house is dry lined looking to connect the two with 6" pipe to give some benefit to the dry lining and cavity but can this be source in builders providers in moderately short lenths (only looking for about 3 meters). I have 4" waste pipe to hand but there's a void to fit 6" and would making sealing easier afterwards.

Calahonda52

Not familiar with Dublin 15
try a kitchen company for good quality flexi,
I know
http://www.lindab.com/ie/ on the Bangor Road do great flexi as it is for zircon
if you go there go around the corner from the main door to the stores
6" rigid in short pieces will be harder, any building sites in D 15?