usually when using a fan duct like that it is to gather more air from an intake vent, or to reduce air turbulence because of a side-mounted intake fan, but in the application they depict, my opinion is GARBAGE, its a waste of money. It doesn't reduce air pressure... its the same fan, blowing the same amount of air, therefore no noise drop, but probably an increase (!) because of the passage of the air through the duct. besides, if you really want one, go to your local hardware shop and get an 80mm wide PVC plumbing pipe and mod-away
<b>Remember, being two-faced is like having two lives with just one set of taxes.</b>