When you install the MSA Airdam or a similar type of Airdam on a 240z / 260z / 280z you can always look through the opening onto the street, which in my opinion looks kinda wrong. So I designed this Adapter to go onto the rectangular duct. 

As these Air Dams are made from fiberglass, it could be that you have to sand the mating surface to match to the adapter. The Adapter itself will be glued on.

It will work by itself and does cover the opening completely, so you cant look onto the ground through the airdam. If you wish, you can also install a 60 mm hose ontop to use the funnel for brake cooling.